I am trying to animate 2 UIButtons in a UITableViewCell called addToPlaylist and removeFromPlayList (they animate off to the right after being swiped on) and am using a block as follows
[UIView animateWithDuration:0.25 animations:^{
self.addToPlaylist.center = CGPointMake(contentsSize.width + (buttonSize.width / 2), (buttonSize.height / 2));
self.removeFromPlaylist.center = CGPointMake(contentsSize.width + (buttonSize.width / 2), (buttonSize.height / 2));
myImage.alpha = 1.0;
}
completion:^ (BOOL finished)
{
if (finished) {
// Revert image view to original.
NSLog(#"Is completed");
self.addToPlaylist.hidden = YES;
self.removeFromPlaylist.hidden = YES;
self.hasSwipeOpen = NO;
}
}];
on completion I want to hide the buttons to attempt to lessen redraw on scroll etc.
This code sits within '-(void) swipeOff' which is called in the UITableViewControllers method scrollViewWillBeginDragging like so:
- (void)scrollViewWillBeginDragging:(UIScrollView *) scrollView
{
for (MediaCellView* cell in [self.tableView visibleCells]) {
if (cell.hasSwipeOpen) {
[cell swipeOff];
}
}
}
The problem is the completion code, if I remove it or set it to nil all is good, if I include it I get an EXC_BAD_ACCESS. even if I include it with any or all of the lines within the if(finished) commented out
Am I using this in the wrong way, any help much appreciated.
Thanks
I had the same problem with animations. I've solved it by removing -weak_library /usr/lib/libSystem.B.dylib from Other Linker flags.
Also, according to this answer, if you need this flag, you may replace it with -weak-lSystem.
Check if you are not calling a UIView (collectionView, Mapview, etc) from inside the UIView block, meaning, it would be a call outside the main thread. If you are, try this:
DispatchQueue.main.async {
self.mapBoxView.setZoomLevel(self.FLYOVERZOOMLEVEL, animated: true
)}
Related
Here's what I want to do. Not sure if it's possible, but if there's an answer with clean code that's app store acceptable I'm more than happy to give a bounty for it!
- Present an MFMessageComposeViewController with a custom animation. (It's
a modal view controller).
- I then want to animate this MFMessageComposeViewController off with a
custom animation, while at the same time animating on a new instance
of MFMessageComposeController. (Again, custom animation).
For the sake of this question, let's make it simple and say that the first MFMessageComposeViewController should slide in from the right, and then it should slide off to the left (when the send button is pressed) while the new instance slides on from the right (pretty much like the default push animation for a nav controller).
If this is impossible, an explanation of why there's no way to do this would be great :)
No. But you can do a trick, which will looks like you wish.
- (IBAction)showComposer:(id)sender {
// 1) get the prepared image of empty composer
UIImageView *composerView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"preparedImage"]];
composerView.frame = rightOffscreenFrame;
[self.view addSubview:composerView];
// 2) do any transitions, and transforms with it
[UIView animateWithDuration:0.33 animations:^{
composerView.frame = self.view.bounds;
} completion:^(BOOL finished) {
if (finished) {
// 3) when it is time, just add a real composer without animation
MFMailComposeViewController *composer = [[MFMailComposeViewController alloc] init];
composer.mailComposeDelegate = self;
[self presentViewController:composer animated:NO completion:^{
[composerView removeFromSuperview];
}];
}
}];
}
- (void)mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error
{
// 4) when user will send message, render the new image with content of composer
UIGraphicsBeginImageContext(self.view.bounds.size);
[controller.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *composerView = [[UIImageView alloc] initWithImage:newImage];
composerView.frame = self.view.bounds;
// 5) show it below composer, close composer without animation.
[self.view addSubview:composerView];
[self dismissViewControllerAnimated:NO completion:^{
// 6) do any transitions, and transforms with image.
[UIView animateWithDuration:0.33 animations:^{
composerView.frame = leftOffscreenFrame
} completion:^(BOOL finished) {
if (finished) {
[composerView removeFromSuperview];
}
}];
}];
}
Well, I have to say you seriously caught my curiosity with this one. Now, as far as your question goes, it doesn't look like there's really that much you can do about this.
I took a couple of different approaches to trying to present the composer in a style other than the default with little success. The closest I was able to get was with this:
UIViewAnimationTransition trans = UIViewAnimationTransitionCurlDown;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationTransition:trans forView:[self view] cache:YES];
[self presentViewController:controller animated:NO completion:nil];
[UIView commitAnimations];
Using this method of presentation the animation effect happened, but it didn't actually seem to apply to the composer. It was just a blank page flipping. I also tried just manually adding transition effects such as alpha, and transform adjustments to the composers view property directly, but that didn't do much either.
Everything just kept boiling down to this:
Important: The message composition interface itself is not
customizable and must not be modified by your application. In
addition, after presenting the interface, your application is unable
to make further changes to the SMS content. The user can edit the
content using the interface, but programmatic changes are ignored.
Thus, you must set the values of content fields, if desired, before
presenting the interface
EDIT: Actually I think I may have found a way to make this work. It still seems unlikely that you'll be able to use custom transitions of any kind, and I can't promise that Apple will approve this, but this should allow you to present the composer navigation controller push style!
Instead of using:
[self presentViewController:controller animated:YES completion:nil];
Use:
[self.navigationController pushViewController:[[controller viewControllers] lastObject] animated:YES];
This actually allows you to push to the composer. By default this behavior isn't supported and causes an error stating that you can not push to and navigation controller (the composer).
Then to follow up, in - (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult)result Simply use:
[self.navigationController popToRootViewControllerAnimated:YES];
Instead of:
[self dismissViewControllerAnimated:YES completion:nil];
EDIT 2: Sorry, looks like I forgot about one of the points of your question. If you want to push from one instance of the composer to another you can create iVars for each composer, set them up in viewDidLoad, and then handle daisy chaining them together in didFinishWithResult. However, this only partially solves the problem. As it stands, the code I've posted below will work fine going forward, but not as well backing up. I believe the reason for this is that the composer expects to be closed and made nil after a message has been successfully sent, and as a result the cancel but is automatically disabled.
Overall, if you mess around with it a little you should still be able to get this working.
- (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult)result {
switch (result) {
case MessageComposeResultCancelled:
if (controller == firstComposer) {
[self.navigationController popToRootViewControllerAnimated:YES];
}
else if (controller == secondComposer) {
[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:1] animated:YES];
}
break;
case MessageComposeResultFailed:
NSLog(#"Failed");
break;
case MessageComposeResultSent:
if (controller == firstComposer) {
[self.navigationController pushViewController:[[secondComposer viewControllers] lastObject] animated:YES];
[secondComposer becomeFirstResponder];
}
break;
default:
break;
}
}
Link to download the project I made this in.
MFMailComposeViewController as a modal view is consistent with Apple's HIG. Pushing it onto a navigation stack is not. Use :
-presentModalViewController:animated:
-presentViewController:animated:completion` (if supporting iOS 5).
if you really want some deferent use the modalTransitionStyle
mail.modalTransitionStyle=UIModalTransitionStyleFlipHorizontal;
mail.modalTransitionStyle=UIModalTransitionStyleCoverVertical;
mail.modalTransitionStyle = UIModalTransitionStylePartialCurl;
mail.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
and also use the modalPresentationStyle.
FMailComposeViewController is a UINavigationController and pushing a navigation controller is not supported..
i don't think it is possible because it is a custom component given by apple
Recently faced this task. I needed to implement a transition similar push and pop of navigation stack.
Here is my implementation:
extension MFMailComposeViewController: UIViewControllerTransitioningDelegate, UIViewControllerAnimatedTransitioning {
convenience init(_ customTransition: Bool) {
self.init()
if customTransition { self.transitioningDelegate = self }
}
public func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
public func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
public func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 1.0
}
public func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let containerView = transitionContext.containerView
guard let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from),
let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
else { return }
var start = transitionContext.initialFrame(for:fromVC)
var end = transitionContext.finalFrame(for:toVC)
if toVC is MFMailComposeViewController {
start.origin.x -= containerView.bounds.width
end.origin.x = 0.0
let v1 = transitionContext.view(forKey:.from)!
let v2 = transitionContext.view(forKey:.to)!
v2.frame.origin.x = containerView.bounds.width
containerView.addSubview(v2)
UIViewPropertyAnimator.runningPropertyAnimator(withDuration: 0.3, delay: 0, options: .curveEaseOut, animations: {
v1.frame.origin.x -= containerView.bounds.width/3
v2.frame = end
}) { _ in
transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
}
} else {
start.origin.x = containerView.bounds.width
end.origin.x = 0.0
let v1 = transitionContext.view(forKey:.from)!
let v2 = transitionContext.view(forKey:.to)!
v2.frame.origin.x = -containerView.bounds.width/3
containerView.insertSubview(v2, belowSubview: v1)
UIViewPropertyAnimator.runningPropertyAnimator(withDuration: 0.3, delay: 0, options: .curveEaseOut, animations: {
v2.frame = end
v1.frame = start
}) { _ in
transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
}
}
}
}
Above, we have implemented an extension for the MFMailComposeViewController, in which the key is an initialization with a line: self.transitioningDelegate = self
Next, we write the pseudo-code of the controller, where the MFMailComposeViewController will be initialized and present with the transition that we need:
class ViewController: UIViewController, MFMailComposeViewControllerDelegate {
#IBAction func testAction(_ sender: UIButton) {
let mailComposerVC = MFMailComposeViewController(true)
mailComposerVC.mailComposeDelegate = self
//then we configure the controller for our needs
self.present(mailComposerVC, animated: true, completion: nil)
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true, completion: {
//configure result
})
}
}
And voila, everything works like a charm!
Its possible, & u can use it as a normal ViewController, in one of my app i used, modalTransistion style as dissolve and its in store...
And one more thing, developer decides how to present the mail composer, and also how to dismiss it.
Presenting & dismissing handled by us not iOS/apple..
So I'm trying to implement the ECSlidingViewController sample into my App.
github source for this
The only thing I'd like to do to modify it, is prevent the TopView from completely sliding off-screen before it changes the contained view, and instead just keep the TopView in place but update it's contained view with it's new view controller that was selected from the menu. The Facebook app's take on this is exactly what I want, in case that sounded confusing.
After looking around for a while within the project, I've determined that it definitely (and obviously) has something to do with this line of code in the ECSlidingViewController.h:
- (void)anchorTopViewOffScreenTo:(ECSide)side animations:(void(^)())animations onComplete:(void(^)())complete;
I looked at where this gets called in the .m:
- (void)anchorTopViewOffScreenTo:(ECSide)side{
[self anchorTopViewOffScreenTo:side animations:nil onComplete:nil];
}
- (void)anchorTopViewOffScreenTo:(ECSide)side animations:(void(^)())animations onComplete:(void(^)())complete
{
CGFloat newCenter = self.topView.center.x;
if (side == ECLeft) {
newCenter = -self.resettedCenter;
} else if (side == ECRight) {
newCenter = self.screenWidth + self.resettedCenter;
}
[self topViewHorizontalCenterWillChange:newCenter];
[UIView animateWithDuration:0.25f animations:^{
if (animations) {
animations();
}
[self updateTopViewHorizontalCenter:newCenter];
} completion:^(BOOL finished){
if (complete) {
complete();
}
_topViewIsOffScreen = YES;
[self addTopViewSnapshot];
dispatch_async(dispatch_get_main_queue(), ^{
NSString *key = (side == ECLeft) ? ECSlidingViewTopDidAnchorLeft : ECSlidingViewTopDidAnchorRight;
[[NSNotificationCenter defaultCenter] postNotificationName:key object:self userInfo:nil];
});
}];
}
This is where I'm guessing the animation is being told how to animate, but I don't understand how any of this could be telling it to move off-screen. Am I overlooking something as simple as replacing something to nil? Perhaps there's another value somewhere that I haven't found? This is my first question on StackOverflow, and though I'm new to Obj-C in general, I have a pretty decent grasp on how it works. So I'm hoping to receive at least a tip in the right direction. Thanks!
Just use the following method
- (void)anchorTopViewTo:(ECSide)side animations:(void (^)())animations onComplete:(void(^)())complete
instead of
- (void)anchorTopViewOffScreenTo:(ECSide)side animations:(void(^)())animations onComplete:(void(^)())complete
If it's just the bouncing that you want to remove, then instead of calling:
[self anchorTopViewOffScreenTo:side animations:nil onComplete:nil];
call directly:
[self.slidingViewController resetTopView];
first of all sorry for my English :-) not so good.
I have a strange memory leak with the following code (code after the explanation).
I have a class, FLWaitingView. It is a simple view with a waiting indicator (plus a view with background), used to say to the user "wait for the data to be loaded".
It has two simple methods: show and dismiss.
In the show method, I find the main Application Window and add the subviews (the waiting view and a background view, with different animations). In the dismiss method, I remove it from superview.
In every show, I verify that the view isn't already visible using a static bool var (is_visible).
The strange thing is this: In the dismiss method, I use:
[self.view removeFromSuperview];
[self.waitingView removeFromSuperview];
to remove the two views from the Window, to avoid them to be retained. They are correctly removed, I can verify this with NSLog (for cicle on each window subview). But, in INSTRUMENTS, using the "mark heap" function, I see that in every single reload (new instance of FLWaitingView, then show, then dismiss) the old instance remains in memory and continues to increase memory usage. Obviously is not a problem of the calling code, because I correctly release the object:
//CALLING CODE
//customWaitingView is a property retained
self.customWaitingView = [[[FLWaitingView alloc]init]autorelease];
[self.customWaitingView show];
Moreover, and I think that this is the most important information, if I move the view dismission in another method, called by a selector, the leak disappear!!!
Now I show the "wrong" code and, after, the "correction". I would like to understand why it happens.
- (void)show
{
if (!is_visible){
id appDelegate = [[UIApplication sharedApplication] delegate];
UIWindow *window = [appDelegate window];
self.waitingLabel.text = #"Attendere";
self.view.alpha = 1.0;
self.waitingView.alpha = 1.0;
[window addSubview:self.view];
[window addSubview:self.waitingView];
[self.waitingIndicator startAnimating];
self.view.frame = window.frame;
self.waitingView.center = window.center;
// "Pop in" animation for alert
[self doPopInAnimationWithDelegate:self];
// "Fade in" animation for background
[self doFadeInAnimation];
is_visible = YES;
} else {
NSLog(#"FLWaitingView %# already visible, do nothing", self);
}
}
- (void)dismiss
{
[UIView beginAnimations:nil context:nil];
self.view.alpha = 0.0;
self.waitingView.alpha = 0.0;
[UIView commitAnimations];
[self.waitingIndicator stopAnimating];
//here is the problem
[self.view removeFromSuperview];
[self.waitingView removeFromSuperview];
is_visible = NO;
}
the code above is the "wrong" one, but if I add
[self performSelector:#selector(alertDidFadeOut) withObject:nil afterDelay:0.5];
in the dismiss method and a new method (obviously removing the redundant code from dismiss method):
- (void)alertDidFadeOut
{
//here the memory is correctly released
[self.view removeFromSuperview];
[self.waitingView removeFromSuperview];
is_visible = NO;
}
the memory is correctly released.
Why??????
Thank you in advance
Fabio
Your view isn't getting released as you would be expecting because at the moment you're releasing it there are still animations linked to it. You can only properly release it after the animations are finished.
Your second method works because the animation lasts less than 0.5 seconds - the releasing code is called after view is freed of all the animations.
Proper way to animate the view would be to either create an animation and assign its delegate or maybe a bit more elegant soulution is to use block-based animation like this:
- (void)dismiss
{
[[UIApplication sharedApplication] beginIgnoringInteractionEvents];
[UIView animateWithDuration: 0.15
animations: ^{
self.view.alpha = 0.0;
self.waitingView.alpha = 0.0;
}
completion: ^(BOOL finished){
[self.waitingIndicator stopAnimating];
[self.view removeFromSuperview];
[self.waitingView removeFromSuperview];
is_visible = NO;
[[UIApplication sharedApplication] endIgnoringInteractionEvents];
}];
}
When the user navigates to a different view and returns back to the original view I would like everything to be reset as though they were coming to the view for the first time.
I was able to stop the audio from playing when they leave, but not an animation method.
how would I be able to do this?
-(void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[audioIntro stop];
[mainAudio stop];
}
here's the animation code:
- (void) firstAnimation {
if (playSoundButton.enabled = NO || audioIntro.playing) {
return;
}
UIViewAnimationOptions options = UIViewAnimationOptionCurveLinear;
myImage.hidden = NO;
myImage.alpha = 1.0;
[UIView animateWithDuration:1.0 delay:12.0 options:options animations:^
{
setAnimationBeginsFromCurrentState:YES;
tapImage.alpha = 0.0;
}
completion:^(BOOL finished){
[self performSelector:#selector(secondAnimation) withObject:nil afterDelay:0.2];
}
];
}
thanks for any help.
It seems a bit hacky - but I would try this:
Use the "old style" animation - i.e. not with blocks - use "beginAnimation", setting an animationID for your animation.
In you viewWillDisappear method, call "beginAnimation" again, with the same animationID, but this time:
a. Set the animation duration to ZERO
b. Animate "to" the location where you want the stuff to reset to.
Set some sort of kill-flag in the viewWillDisappear method
Make the completion function look for the "kill flag" - and do not evoke the second animation inside your "secondAnimation" flag if the selector if the "kill flag" is set.
(I am a little unclear - if the "finished" flag would suffice for the "kill-flag" - not having seen your entire code.
I'm building a custom slot machine with a column that exists of a uitableview.
When the user pulls a lever the tableview should scroll to a certain position with an index.
I used the method:
- scrollToRowAtIndexPath:atScrollPosition:animated:
But this method will make the table scroll with a constant duration. So you will not really recognize a long or short spin.
I'm looking for a way to:
A) Slow down the scroll animation. Or,
B) Change the duration for the scroll animation to a self defined value.
The normal scroll animation (with the finger) does show this effect.
Maybe it is a stupid idea, but is it an idea to invoke a touchesBegan and touchesDidEnd method on my tableView?
Thanks already
May need to look in that direction?
[UIView animateWithDuration: 1.0
animations: ^{
[tableViewExercises scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:previousSelectedExerciseCell inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:NO];
}completion: ^(BOOL finished){
}
];
Work only with animated:NO.
Because a UITableView inherits from UIScrollView you might also use setContentOffset:animated:
This way you can make your tableview "scroll" a certain amount of pixels of your choosing to any side you like.
This can be done the same with the scrollToRowAtIndexPath:atScrollPosition:animated:
I made a prototype just to show you how it works.
Because this is done with timers and stuff you can set how long the autoScroll will last and how fast (and how far if you're using the contentoffset) the animation will go.
This is the .h file:
#import <UIKit/UIKit.h>
#interface AutomaticTableViewScrollViewController : UIViewController <UITableViewDelegate,UITableViewDataSource>
{
UITableView *slotMachine;
NSMutableArray *listOfItems;
NSTimer *tableTimer;
}
#property (nonatomic,retain) UITableView *slotmachine;
#property (nonatomic,retain) NSMutableArray *listOfItems;
#property (nonatomic,retain) NSTimer *tableTimer;
-(void)automaticScroll;
-(void)stopscroll;
#end
This is the .m file:
#import "AutomaticTableViewScrollViewController.h"
#implementation AutomaticTableViewScrollViewController
#synthesize slotmachine;
#synthesize listOfItems;
#synthesize tableTimer;
-(void)loadView
{
[super loadView];
slotmachine = [[UITableView alloc] initWithFrame:self.view.frame style:UITableViewStylePlain];
slotmachine.delegate = self;
slotmachine.dataSource = self;
[self.view addSubview:slotmachine];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
// Set up the cell...
if (indexPath.row % 2 == 0)
{
cell.textLabel.text = #"blalala";
}
return cell;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 99999;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
//you might want to do this action in ur buttonTargetMethod
//start timers
tableTimer = [NSTimer scheduledTimerWithTimeInterval:0.2 //this value arranges the speed of the autoScroll
target:self
selector:#selector(automaticScroll)
userInfo:nil
repeats:YES];
[NSTimer scheduledTimerWithTimeInterval:5 //this arranges the duration of the scroll
target:self
selector:#selector(stopscroll)
userInfo:nil
repeats:NO];
}
-(void)automaticScroll
{
[slotmachine setContentOffset:CGPointMake(slotmachine.contentOffset.x, slotmachine.contentOffset.y + 50) animated:YES]; //the 50 stands for the amount of movement every tick the timer will make
}
-(void)stopscroll
{
//stop tabletimer again
[tableTimer invalidate];
}
-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
{
return YES;
}
#end
If you have any question feel free to leave a comment and I will elaborate.
If you can require iOS 5, you could use the UIScrollViewDelegate method scrollViewWillEndDragging:withVelocity:targetContentOffset:.
This allows you to see, how fast the user was moving the finger, where the deceleration animation would end with the default speed, and it allows you to override the animation speed, so that it ends at a different point.
the common way to make apps-slot-machines is with UIPickerView maybe you should check this..
How about setup a timer and then call the scroll when timer fires:
start_index = 0;
dest_index = 20;
timer = [NSTimer scheduledTimerWithTimeInterval:(0.1) target:self selector:#selector(rolling) userInfo:nil repeats:YES];
- (void)rolling {
start_index++;
if (start_index < dest_index) {
NSIndexPath *Index = [NSIndexPath indexPathForRow:start_index inSection:0];
[self.tableView scrollToRowAtIndexPath:Index atScrollPosition:UITableViewScrollPositionMiddle animated:NO];
} else {
[timer invalidate];
}
}
I've been using the Sparrow framework's tweening features to do similar animations.
The link above has an example of how to set it up. You can animate any numeric property of any Objective C object, and you can use transitions like "easy in", "ease out", "ease in elastic", etc., or just good old linear animations.
The property contentSize is a CGPoint though, so you would need actually animate a different property on one of your classes and then implement an actual method for the property setter function so that it updates the contentOffset.
- (void) setTableScrollPosition:(CGFloat)position
{
CGPoint newOffset = CGPointMake(0.0, position);
scrollView.contentOffset = newOffset;
}
I searched a lot for this answer but ultimately had to come up with one of my own.
You can call the method scrollAutomatically with the starting row number like:
[self scrollAutomatically:0];
So this is what the function looked like. I was dealing with a table which always had 3000 rows and I intended to scroll to the bottom.
- (void) scrollAutomatically:(int) i
{
__block int j = i;
[UIView animateWithDuration: 0//Change this to something more for slower scrolls
animations: ^{
[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:j inSection:0] atScrollPosition:UITableViewScrollPositionBottom animated:NO];
}
completion: ^(BOOL finished){
j = j + 10;//Changing this number affects speed.
if(j<=2999)//here you could provide the index of destination row
[self scrollAutomatically:j];
else
{
//I had some code here that popped up a UIAlertView.
}
}];
}
Now coming to the speed of the scroll.
FOR REALLY FAST SCROLLS:
If I set value by which I increment the row index (j) on each call of the function to 10,
i.e. if I write j = j+10; then my 3000 rows took about 9 seconds to scroll. (3000 * mean FPS that I could muster).
If I set it to j = j+20; then the 3000 rows took about 4.5 seconds. So you get the idea.
To make it scroll slower reduce the increment value.
FOR SLOW, READABLE SCROLLS:
[UIView animateWithDuration: 1.5//this will directly set your speed. n rows scrolled every 1.5 seconds.
NOTE: If you change frames of CALayers or Views (eg. a customView you may have added to the contentView of your tableViewCell), then those animations will start to bother you here. For a large animation duration, they will be very visible and you may see strange cell beahviour.
In that case wherever you change your frames etc. look at something like:
[CATransaction begin];
[CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];
[myView.myCALayer.frame = (CGRect){ { 10, 10 }, { 100, 100 } ];
[CATransaction commit];
Find the above solution here.
You may also have to set the actions dictionary for the layer to return nulls for all actions.
NSMutableDictionary *newActions = [[NSMutableDictionary alloc] initWithObjectsAndKeys:[NSNull null], #"sublayers", nil];
superlayer.actions = newActions;
This seems to be too late but for people facing the same problem I hope this answer will be helpful. Also please feel free to guide me in case I have made some obvious (or not so much) blunder.
Edit: Oops, I see the exact thing above my answer :(
Anyways, this is a bit more detailed and I am only a beginner :)
You can't (to my knowledge, I have been looking everywhere for a way to do this) make a speed that isn't constant for
- scrollToRowAtIndexPath:atScrollPosition:animated:
So I would suggest... that if you really need it, make your own out of some animation or something, or do something alot easier that would save you some time, use UIPickerView