I'm new to iOS programming, and I'm having trouble with getting a UIScrollView to move when editing a UITextField that is obscured by the keyboard. The code is straight out of Apple's documentation but it's not working for some reason.
Through debugging I've found that the notifications seem to be getting passed correctly (i.e. it logs "View should resize", but only when activeField is the textField that is under the keyboard) and scrollpoint is being set correctly, but the scrollview still does not move. Also, I'm reasonably sure that the delegation pattern is correct (ViewController is delegate of textFields as well as scrollView)
- (void)keyboardWasShown:(NSNotification*)aNotification
{
NSDictionary* info = [aNotification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
// If active text field is hidden by keyboard, scroll it so it's visible
// Your application might not need or want this behavior.
CGRect aRect = self.view.frame;
aRect.size.height -= kbSize.height;
if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
CGPoint scrollPoint = CGPointMake(0.0, activeField.frame.origin.y-kbSize.height);
[scrollView setContentOffset:scrollPoint animated:YES];
NSLog(#"%#",#"view should resize");
}
}
Seeing as the code is straight from the documentation, I'm probably just missing something simple. Can anyone point me in the direction of things to check for?
Apple's example has a bug in that it doesn't explicitly set the scroll view's content size and thus uses the default content size which is (0, 0). I fixed this problem by adding this code in my view controller:
- (void)viewDidLoad
{
[super viewDidLoad];
// Set the scroll view's content size to be the same width as the
// application's frame but set its height to be the height of the
// application frame minus the height of the navigation bar's frame
CGRect applicationFrame = [[UIScreen mainScreen] applicationFrame];
CGRect navigationFrame = [[self.navigationController navigationBar] frame];
CGFloat height = applicationFrame.size.height - navigationFrame.size.height;
CGSize newContentSize = CGSizeMake(applicationFrame.size.width, height);
((UIScrollView *)self.view).contentSize = newContentSize;
}
Related
I have a UITextView on which I am using an NSLayoutConstraint to dodge the keyboard. Here's the constraint:
self.textViewBottomConstraint = [NSLayoutConstraint constraintWithItem:textView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0.0];
[self.view addConstraint:self.textViewBottomConstraint];
When the keyboard shows/hides I animate the constraint by setting the constraint constant to the keyboard height. However, doing so for some reason resets the contentSize to {0,0}, thus breaking scrolling. I've added a hack to handleKeyboardDidHide: to reset the contentSize to what it was before being reset, but this has some ugly side effects such as the scroll position being reset and the view not scrolling to the cursor position until typing starts.
- (void) handleKeyboardDidShow:(NSNotification *)notification
{
CGFloat height = [KeyboardObserver sharedInstance].keyboardFrame.size.height;
self.textView.constant = -height;
[self.view layoutIfNeeded];
}
- (void) handleKeyboardDidHide:(NSNotification *)notification
{
// for some reason, setting the bottom constraint resets the contentSize to {0,0}...
// so let's save it before and reset it after.
// HACK
CGSize size = self.textView.contentSize;
self.textView.constant = 0.0;
[self.view layoutIfNeeded];
self.textView.contentSize = size;
}
Anyone know how to avoid this issue altogether?
I don't know what's wrong with your code, and we can deal with that in detail if you want. But as an initial suggestion, if possible, don't resize the UITextView: just change its content and scroll insets, like this:
- (void) keyboardShow: (NSNotification*) n {
NSDictionary* d = [n userInfo];
CGRect r = [d[UIKeyboardFrameEndUserInfoKey] CGRectValue];
self.tv.contentInset = UIEdgeInsetsMake(0,0,r.size.height,0);
self.tv.scrollIndicatorInsets = UIEdgeInsetsMake(0,0,r.size.height,0);
}
Even so, I find that you have to wait until the keyboard hide animation completes before resetting those values:
- (void) keyboardHide: (NSNotification*) n {
NSDictionary* d = [n userInfo];
NSNumber* curve = d[UIKeyboardAnimationCurveUserInfoKey];
NSNumber* duration = d[UIKeyboardAnimationDurationUserInfoKey];
[UIView animateWithDuration:duration.floatValue delay:0
options:curve.integerValue << 16
animations:
^{
[self.tv setContentOffset:CGPointZero];
} completion:^(BOOL finished) {
self.tv.contentInset = UIEdgeInsetsZero;
self.tv.scrollIndicatorInsets = UIEdgeInsetsZero;
}];
}
(It may be that that trick would help your code somehow as well.)
Basing on:
https://developer.apple.com/library/ios/#documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html
I have implemented a feature that scrolls the view automatically whenever keyboard hides selected text input (mine and the one from tutorial are actually the same).
Unfortunately, there is an undesirable behaviour: my scrollView's contentSize property gets increased by the height of the keyboard. So when keyboard is still visible I can scroll the view, but below proper content a blank space appears. This is a thing I would like to avoid. I'm aware this is caused by changing contentInset property, so maybe there is another way to do this thing without side-effects.
At first I register observers for UIKeyboardDidShowNotification and UIKeyboardWillHideNotification:
- (void)registerKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(keyboardWillBeHidden:) name:UIKeyboardWillHideNotification object:nil];
}
this function is called in viewWillAppear. Methods keyboardWasShown and keyboardWillBeHidden look as following:
- (void)keyboardWasShown:(NSNotification *)notification
{
NSDictionary *info = [notification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
CGRect rect = self.view.frame;
rect.size.height -= kbSize.height;
if(!CGRectContainsPoint(rect, activeField.frame.origin)) {
CGPoint scrollPoint = CGPointMake(0.0, 2*activeField.frame.size.height+activeField.frame.origin.y-kbSize.height);
[scrollView setContentOffset:scrollPoint animated:YES];
}
}
- (void)keyboardWillBeHidden:(NSNotification *)notification
{
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
}
As I wrote earlier, it is basically Apple's solution.
Content inset is meant to allow access to parts of the scroll view that might appear hidden below keyboard (for example). So if you had a text view on the bottom of your content, the user would not be able to interact with it, as it would be hidden beneath the keyboard window. With content inset (as per the Apple example), you are able to scroll it more, and reveal the text view. It doesn't actually increase the contentSize property.
Please read more here:
http://developer.apple.com/library/ios/#documentation/WindowsViews/Conceptual/UIScrollView_pg/CreatingBasicScrollViews/CreatingBasicScrollViews.html
CGFloat contentSizeHeight = contentSize.height;
CGFloat collectionViewFrameHeight = self.collectionView.frame.size.height;
CGFloat collectionViewBottomInset = self.collectionView.contentInset.bottom;
CGFloat collectionViewTopInset = self.collectionView.contentInset.top;
CGPoint bottomOffsetForContentSize = CGPointMake(0, MAX(-collectionViewTopInset, contentSizeHeight - (collectionViewFrameHeight - collectionViewBottomInset)));
[self.collectionView setContentOffset:bottomOffsetForContentSize animated:animated];
I want to create a subclass of UITableView or UIScrollView that will have some shading at the top when the content offset is > 0 to indicate that the content is scrollable. (See image attached)
The way I'm implementing it right now is using the UIViewController that is the delegate of the tableView. I simply have a GradientView on top of the tableView, and I intercept scrollViewDidScroll: to animate the visibility of that top gradient.
My problem with this implementation is that it's not "clean". I want my UIViewControllers to take care of logic, and not to deal with applying gradients and stuff. I wish I could just drop a subclass of UITableView that will do that for me.
The challenge for me is that I can't figure out how the tableView could add to itself a fixed content on top of the scrollable content.
Another question is what method/s of UIScrollView should I override to intercept the scrolling event. Obviously I don't want the tableView to be the delegate of itself...
Any ideas?
Thanks!
Ok, so I found the solution on Apple's WWDC 2011 Session 104 video - Advanced Scroll View Techniques.
There is a whole section in this video about "Stationary Views" inside a scroll view.
According to Apple, the way to go here is to override layoutSubviews and put there all the code to position whatever you want - wherever you want.
I tried it and it's actually pretty easy and it's working as expected.
So for example if I would like a shadowed header on top of the table when the content is being scrolled, this is the code I should write:
-(void) layoutSubviews
{
[super layoutSubviews];
[self positionTopShadow];
}
-(void) positionTopShadow
{
CGFloat yOffset = self.contentOffset.y;
// I'm doing some limiting so that the maximum height of the shadow view will be 40 pixels
yOffset = MIN(yOffset, 40);
yOffset = MAX(0, yOffset);
CGRect frame = self.topShadowView.frame;
// The origin should be exactly like the content offset so it would look like
// the shadow is at the top of the table (when it's actually just part of the content)
frame.origin = CGPointMake(0, self.contentOffset.y);
frame.size.height = yOffset;
frame.size.width = self.frame.size.width;
self.topShadowView.frame = frame;
if (self.topShadowView.superview == nil)
{
[self addSubview:self.topShadowView];
}
[self bringSubviewToFront:self.topShadowView];
}
I've managed to figure out a much simpler way of doing this then what Avraham did.
I use the fact that the UIScrollView calls scrollViewDidScroll: ever pixel the scrolling changes to set the object at the location of the offset. Below is my full code to keep a gray bar at the top of the scrollview as you move around:
- (void)viewDidLoad {
UIScrollView* scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(5.0, 50.0, self.bounds.size.width - 15.0, self.bounds.size.height - 60.0)];
[scrollView setBackgroundColor:[UIColor colorWithRed:251.0/255.0 green:251.0/255.0 blue:251.0/255.0 alpha:1.0]];
[scrollView setContentSize:CGSizeMake(scrollView.frame.size.width + 500, 1000.0)];
[scrollView setDelegate:self];
[self addSubview:scrollView];
UIView* header = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, scrollView.contentSize.width, 40.0)];
[header setTag:100];
[header setBackgroundColor:[UIColor darkGrayColor]];
[scrollView addSubview:header];
}
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
UIView* header = [self viewWithTag:100];
[header setFrame:CGRectMake(0.0, scrollView.contentOffset.y, header.bounds.size.width, header.bounds.size.height)];
}
You could try using viewForHeaderInSection method of tableView for the shaded view(and also heightForHeaderInSection)... Make the shaded portion as a header.That way there is a fixed content on top of the scrollable content.
#define kImageOriginHight 300
- (void)scrollViewDidScroll:(UIScrollView *)scrollView1{
CGFloat yOffset = scrollView1.contentOffset.y;
// NSLog(#" y offset := %f", yOffset);
//zoom images and hide upper view while scrooling to down position
if (yOffset < 0) {//-kImageOriginHight
CGRect f = imgV.frame;
f.origin.y = yOffset;
f.size.height = -yOffset + kImageOriginHight;
imgV.frame = f;
//viewTableUpperView.alpha = 1.5 - (yOffset/-kImageOriginHight);
//viewTableUpperView.userInteractionEnabled = NO;
if(yOffset+0.5 == -kImageOriginHight){
[UIView animateWithDuration:0.1 animations:^{
//viewTableUpperView.alpha = 1.0;
}];
//viewTableUpperView.userInteractionEnabled = YES;
}
}
}
I have a text view (nib-file) with a UITextView maximised the entire view.
When ever i push the viewcontroller on to the navigationcontroller i load the keyboard in the text view's viewDidLoad method.
My problem is that when i write text that has more lines than there is space for, the text is behind the keyboard. I followed the sampe from Apple here.
If i log the "newTextViewFrame" it's NULL. but if i debug the thing it has a fine value.
Even if i hardcode it, the UITextView doesent change size.
Here is my code:
- (void)keyboardWillShow:(NSNotification *)notification {
/*
Reduce the size of the text view so that it's not obscured by the keyboard.
Animate the resize so that it's in sync with the appearance of the keyboard.
*/
NSDictionary *userInfo = [notification userInfo];
// Get the origin of the keyboard when it's displayed.
NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
// Get the top of the keyboard as the y coordinate of its origin in self's view's coordinate system. The bottom of the text view's frame should align with the top of the keyboard's final position.
CGRect keyboardRect = [aValue CGRectValue];
keyboardRect = [self.view convertRect:keyboardRect fromView:nil];
CGFloat keyboardTop = keyboardRect.origin.y;
CGRect newTextViewFrame = self.view.bounds;
newTextViewFrame.size.height = keyboardTop; - (self.view.bounds.origin.y);
// Get the duration of the animation.
NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
NSTimeInterval animationDuration;
[animationDurationValue getValue:&animationDuration];
// Animate the resize of the text view's frame in sync with the keyboard's appearance.
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:animationDuration];
createListingTextView.frame = newTextViewFrame;
[UIView commitAnimations];
NSLog(#"Textview resized: %#", newTextViewFrame);
}
My task i simple: Implement a View with a UITextView and the keyboard open and scroll the UITextView when ever the text exceeds.
Please advice...
There is a semi-colon after keyboardTop on the line
newTextViewFrame.size.height = keyboardTop; - (self.view.bounds.origin.y);
This would certainly prevent newTextViewFrame from getting the adjusted height.
I'm trying to implement a UITextView in a table cell at the bottom of a table view.
I've tried the suggestions here Making a UITableView scroll when text field is selected, and other solutions as well, but they're a bit different because I have to artificially add extra height to the current view in order to create space for the keyboard.
Here's what I added to the previous solution in order to port it to my app.
-(void) keyboardWillShow:(NSNotification *)note {
CGRect frame = self.view.frame;
frame.size.height += keyboardHeight;
frame.origin.y -= keyboardHeight;
self.view.frame = frame;
}
-(void) keyboardWillHide:(NSNotification *)note
{
CGRect frame = self.view.frame;
frame.size.height -= keyboardHeight;
frame.origin.y += keyboardHeight;
}
Doing this will correctly add the height to the view and scroll to the cell, but after restoring the original view's height, scrolling beyond the current visible view becomes impossible, even though there is valid content outside of the boundaries (I see the text view before the scroll bar bounces back).
If I try to save the tableview's frame or bounds (not the view) in keyboardWillShow and restore them in keyboardWillHide, the scrolling will be restored, but the view will be cut in half.
Are there any remedies to this besides hard-coding the additional height to the bottom of the view?
I was able to solve my problem of the locked scrolling by removing the code that edits the view's origin. In addition, I implemented scrolling to the bottom cell by using the tableview's contentSize property in my calculations.
-(void) keyboardWillShow:(NSNotification *)note
{
if(!isKeyboardShowing)
{
isKeyboardShowing = YES;
CGRect keyboardBounds;
[[note.userInfo valueForKey:UIKeyboardBoundsUserInfoKey] getValue: &keyboardBounds];
CGFloat keyboardHeight = keyboardBounds.size.height;
CGRect frame = self.view.frame;
frame.size.height += keyboardHeight;
self.view.frame = frame;
CGPoint scrollPoint = frame.origin;
scrollPoint.y += _tableView.contentSize.height - keyboardHeight;
[_tableView setContentOffset:scrollPoint animated:YES];
}
}