When is it possible to know the exact size of a UIViewController's view?
The Problem
I have a multi-line UILabel whose frame depends of its text and the width of the parent view. Given that I need to position other views below the UILabel, it's important to make its frame cover exactly the space of the text.
I currently calculate the size like this on viewDidLoad:
labelSize = [text sizeWithFont:font constrainedToSize:CGSizeMake(self.view.frame.size.width, MAX_HEIGHT)];
The problem is that the width of the parent view changes when the UIViewController is used as a modal form sheet or a popover. If I use autoresizingMask the frame of the UILabel is adjusted accordingly, but it no longer is an exact fit for the text.
Where can I calculate the frame of this UILabel knowing the exact size of the UIViewController's view?
Debugging Efforts
This is the result of printing self.view.frame when showing the UIViewController as a modal form sheet (UIModalPresentationFormSheet).
viewDidLoad: (0.000000;0.000000;320.000000;480.000000)
viewWillAppear: (0.000000;0.000000;768.000000;960.000000)
afterDelay: (0.000000;0.000000;540.000000;576.000000)
The code that produces the above output:
- (void)viewDidLoad {
[super viewDidLoad];
[Utils logFrame:self.view.frame tag:#"viewDidLoad"];
}
- (void) viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[Utils logFrame:self.view.frame tag:#"viewWillAppear"];
[self performSelector:#selector(afterDelay) withObject:nil afterDelay:0.1];
}
- (void) afterDelay {
[Utils logFrame:self.view.frame tag:#"afterDelay"];
}
That's because your UIViewController's root view is using autoresizingMask. I don't think there is a "perfect timing" to detect the size of your UIViewController's root view unless you override your root view's 'layoutSubviews' method.
If you don't want your view to be automatically resized, just don't use autoresizing and set the size by yourself, it will always be the same size you expected.
If you are not sure what kind of autoresizingMasks your root view is using, NSLog is your friend.
This looks like a bug, the value should be known in viewWillAppear.
The alternative is to subclass your UIView and override layoutSubviews there to arrange the subviews based on content. You'll then have to call [self.view setNeedsLayout] from your view controller every time you update the contents of the label. The system will call it if the view resizes, so that should have you covered.
Try this for finding the label size,
labelSize = [text sizeWithFont:font constrainedToSize:CGSizeMake(self.label.frame.size.width, MAX_HEIGHT)];
Instead of using the view's width, use the label's width in the constrain size. This should be available in the viewDidLoad, viewDidApper methods of the view controller.
try viewWillAppear. There is no reason for not knowing the size before the the view is about to shown
Related
I have a scrollview inside which i have 20 UItextviews. The scrollview is not working. I have set the following in viewdidload.
self.MainScroll.contentSize = CGSizeMake(320, 1800);
Still it doesn't scroll. However, if i give bounce vertically, it just bounces. My scrollview is a child of the main UIview of dimension 320*600. Please guide how to enable the scroll!!
There are two ways you can get the scrolling to work.
Approach 1 (with code):
1) Pin UIScrollView to the sides of its parent view, as mentioned below.
2) Set content size of your scroll view in viewDidLayoutSubviews:
- (void)viewDidLayoutSubviews {
self.MainScroll.contentSize = CGSizeMake(320, 1800);
}
Approach 2 (pure IB, no code required):
1) Setting contentSize is not required if using AutoLayout. You need to pin your UIScrollView to the parent view as mentioned below:
2) Then add another UIView inside UIScrollView to act as a content view and pin it to the UIScrollView and move all controls inside this content view:
3) Pin content view to its parent scroll view as mentioned below:
4) Set your UIViewController's Simulated Metrics to Freeform (this is important):
5) Size your content UIView to your desired height (obviously important too):
Apple article explaining UIScrollView and AutoLayouts:
https://developer.apple.com/library/content/technotes/tn2154/_index.html
Update the content size after some delay as below.
- (void)viewDidLayoutSubviews {
[self performSelector:#selector(updateContentSize)
withObject:nil
afterDelay:0.25];
}
-(void)updateContentSize{
UIView *viewLast = [viewContent viewWithTag:100];
scrollViewAd.contentSize = CGSizeMake([UIScreen mainScreen].bounds.size.width, CGRectGetMaxY(viewLast.frame));
}
I'm a newbie at objective C programming, so please excuse me if this question has a trivial answer.
I wanted to create a UIScrollview that's larger than the screen size. In order to be able to place all the subviews appropriately inside that main view, I tried the trick suggested in this post.
In this large UIScrollView I have several subviews, such as a ToolbarView, UITextView, UIButtons and container view.
During startup I start setupView to update the frame size of the textview based on the actual screen size. I managed to do this in a separate nib file without too much trouble, but when I try this in the storyboard, a strange thing happens: the UITextView (paperlist) gets initialized and a text is set to it. However, when I try to get the frame size it results in a CGRectwith zero size.
hereunder a snippet of the code I wrote:
- (void)viewWillAppear:(BOOL)animated
{
[super viewDidLoad];
[self setupView];
// Do any additional setup after loading the view.
}
#pragma mark update the view
- (void)setupView {
// first update the paperlist height in function of the screen size of the device used
CGFloat statusBarHeight = [[UIApplication sharedApplication] statusBarFrame].size.height;
CGRect newMainFrame = self.view.frame;
CGRect newPaperlistFrame = self.paperlist.frame;
newPaperlistFrame.size.height = [UIScreen mainScreen].bounds.size.height - KEYBOARD_LOWERBORDER - self.mainToolbar.bounds.size.height - statusBarHeight;
newMainFrame.size.height = self.mainToolbar.bounds.size.height + newPaperlistFrame.size.height + self.fullKeyboardView.frame.size.height;
self.view.frame = newMainFrame;
self.paperlist.frame = newPaperlistFrame;
}
Can anybody help??
thanks in advance!
Julien
That's probably because in viewWillAppear the subviews frames are not completly initialized yet. Instead, try to call your method in this method of your viewController:
-(void)viewDidLayoutSubviews
{
[super viewDidLayoutSubviews];
[self setupView];
}
See more information here: ScrollView created in storyboard initialized with frame 0,0,0,0
My UIScrollView is a ~4500px horizontal view that the user needs to scroll horizontally through to view the content.
I have set it up as follows:
- (void)viewDidLoad
{
[super viewDidLoad];
sview.frame = CGRectMake(0, 0, 568, 320);
sview.contentSize = CGSizeMake(4500, 320);
[sview setScrollEnabled:YES];
}
Yet the scroll view does nothing. Is there something obvious I missed? i've tried literally every tutorial on the web.
I got similar issue. I did following modifications and the scrollView started scrolling for me:
Select to check the 'Bounce Horizontally' property for UIScrollView
in xib.
Move the code following code to viewDidAppear instead of
viewDidLoad:
-(void) viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
sview.frame = CGRectMake(0, 0, 568, 320);
sview.contentSize = CGSizeMake(4500, 320);
[sview setScrollEnabled:YES];
}
I think this should help you.
I've explained it here, but there are so many answers to this problem that suggests turning off Auto Layout. That fixes the problem but that's not really the correct solution. Here's my answer:
Turning Auto Layout works, but that's not the solution. If you really need Auto Layout, then use it, if you don't need it, turn it off. But that is not the correct fix for this solution.
UIScrollView works differently with other views in Auto Layout. Here is Apple's release note on Auto Layout, I've copied the interesting bit:
Here are some notes regarding Auto Layout support for UIScrollView:
In general, Auto Layout considers the top, left, bottom, and right edges of a view to be the visible edges. That is, if you pin a view to
the left edge of its superview, you’re really pinning it to the
minimum x-value of the superview’s bounds. Changing the bounds origin
of the superview does not change the position of the view.
The UIScrollView class scrolls its content by changing the origin of its bounds. To make this work with Auto Layout, the top, left, bottom,
and right edges within a scroll view now mean the edges of its content
view.
The constraints on the subviews of the scroll view must result in a size to fill, which is then interpreted as the content size of the
scroll view. (This should not be confused with the
intrinsicContentSize method used for Auto Layout.) To size the scroll
view’s frame with Auto Layout, constraints must either be explicit
regarding the width and height of the scroll view, or the edges of the
scroll view must be tied to views outside of its subtree.
Note that you can make a subview of the scroll view appear to float (not scroll) over the other scrolling content by creating constraints
between the view and a view outside the scroll view’s subtree, such as
the scroll view’s superview.
Apple then goes on to show example of how to correctly use UIScrollView with Auto Layout.
As a general rule, one of the easiest fix is to create a constraint between the element to the bottom of the UIScrollView. So in the element that you want to be at the bottom of the UIScrollView, create this bottom space constraint:
Once again, if you do not want to use Auto Layout, then turn it off. You can then set the contentSize the usual way. But what you should understand is that this is an intended behaviour of Auto Layout.
First of all you have to add some content to UIScrollSiew as subview for scrolling,without content on UIScrollView how can you scroll?. Here is what i did,just add UIImageView to UIScrollView as subview of size same as size of UIScrollView...
In viewDidLoad method try the following code..
-(void)viewDidLoad
{
UIScrollView *scroll=[[UIScrollView alloc] init];
scroll.frame=CGRectMake(0, 0, 320, 460);
UIImageView *imageView=[[UIImageView alloc] init];
imageView.frame=CGRectMake(0, 0, 320,460);
imageView.image=[UIImage imageNamed:#"chiranjeevi.jpeg"];
scroll.contentSize = CGSizeMake(4500, 460);
[scroll setScrollEnabled:YES];
[scroll addSubview:imageView];
[self.view addSubview:scroll];
}
I tested this code it works well.I hope this code will be helpful to you..
I assume you are adding UISrollingView in your Xib file. This will work for you.
sview.delegate = self;
sview.backgroundColor=[UIColor clearColor];
[sview setCanCancelContentTouches:NO];
sview.indicatorStyle = UIScrollViewIndicatorStyleWhite;
sview.clipsToBounds = YES;
sview.scrollEnabled = YES;
sview.contentSize = CGSizeMake(320,570);
CGPoint topOffset = CGPointMake(0,0);
[sview setContentOffset:topOffset animated:YES];
Also, make sure to give IBOutlet connection in your Xib file.
I also faced the same issue.I added the scroll view in xib.I also added some subviews to this scroll view. The scroll view would stop scrolling after I added the subviews. The solution for this problem was in the xib for the view in file inspector Use Autolayout was checked. I unchecked it and the scroll view scrolled after adding the subviews.
The solution was uncheking the Use Autolayout in file inspector in xib.
I have seen this question being addressed several times here at SO, e.g Problem with UIScrollView Content Offset, but I´m still not able to solve it.
My iphone app is basically a tab bar controller with navigation bar. I have a tableview controller made programmatically and a DetailViewController that slides in when I tap a cell in my tableview controller.
The DetailViewController is made in IB and has the following hierarchy:
top view => UIScrollView => UIView => UIImage and a UITextField.
My goal is to be able to scroll the image and text field and this works well. The problem is that my UIScrollView always gets positioned at the bottom instead at the top.
After recommendations her at SO, I have made my UIScrollView same size as the top view and instead made the UIView with the max height (1500) of my variable contents.
In ViewDidLoad I set the contentSize for the UIScrollView (as this is not accessible from IB):
- (void)viewDidLoad {
[scrollView setContentSize:CGSizeMake(320, 1500)];
[scrollView setContentOffset:CGPointMake(0, 0) animated:YES];
NSLog(#"viewDidLoad: contentOffset y: %f",[scrollView contentOffset].y);
}
Specifically setting the contentOffset, I would expect my scrollView to always end up at the top. Instead it always go to the bottom. It looks to me that there is some autoscrolling beyond my control taking place after this method.
My read back of the contentOffset looks OK. It looks to me that there may be some timing related issues as the scrolling result may vary whether animation is YES or NO.
A ugly workaround I have found is by using this delegate method:
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrView {
NSLog(#"Prog. scrolling ended");
[scrollView setContentOffset:CGPointMake(0, 0) animated:YES];
}
This brings my scrollview to top, but makes it bounce down and up like a yo-yo
Another clue might be that although my instance variables for the IBOutlet are set before I push the view controller, the first time comes up with empty image and textfield:
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
if (!detailViewController) {
detailViewController = [[DayDetailViewController alloc] init];
}
// Pass dictionary for the selected event to next controller
NSDictionary *dict = [eventsDay objectAtIndex:[indexPath row]];
// This method sets values for the image and textfield outlets
[detailViewController setEventDictionary:dict];
// Push it onto the top of the navigation controller´s stack.
[[self navigationController] pushViewController:detailViewController animated:NO];
}
If I set animation to YES, and switch the order of the IBOutlet setting and pushViewController, I can avoid the emptiness upon initialization. Why?
Any help with these matters are highly appreciated, as this is really driving me nuts!
Inspired of Ponchotg´s description of a programmatically approach, I decided to skip interface builder. The result was in some way disappointing: The same problem, with the scrollview ending up in unpredictable positions (mostly at bottom), persisted.
However, I noticed that the scroll offset error was much smaller. I think this is related to the now dynamic (and generally smaller) value of ContentOffset. After some blind experimenting I ended up setting
[textView setScrollEnabled:YES];
This was previously set to NO, as the UITextView is placed inside the scrollview, which should take care of the scrolling. (In my initial question, I have erroneously said it was a UITextField, that was wrong)
With this change my problem disappeared, I was simply not able to get into the situation with scrollview appearing at bottom anymore in the simulator! (At my 3G device I have seen a slight offset appear very seldom, but this is easily fixed with scrollViewDidEndScrollingAnimation delegate described previously ).
I consider this as solved now, but would appreciate if anyone understand why this little detail messes up things?
OK! i have a question before i can give a correct answer.
Why are you using a UIView inside the Scrollview?
You can always only put your UIImageView and UITextField inside the UIScrollView without the UIView
and set the contentSize dynamically depending on the size of the text.
to give you an example how i do it:
int contSize = 0;
imageView.frame = CGRectMake(10, 0, 300, 190);
imageView.image = [UIImage imageNamed:#"yourimage"];
contSize = 190 //or add extra space if you dont want your image and your text to be so close
[textField setScrollEnabled:NO];
textField.font = [UIFont systemFontOfSize:15];
textField.textColor = [UIColor grayColor];
textField.text = #"YOUR TEXT";
[textField setEditable:NO];
textField.frame = CGRectMake(5, contSize, 310, 34);
CGRect frameText = textField.frame;
frameText.size.height = textField.contentSize.height;
textField.frame = frameText;
contSize += (textField.contentSize.height);
[scrollView setScrollEnabled:YES];
[scrolView setContentSize:CGSizeMake(320, contSize)];
In the above example I first create an int to keep track of the ysize of my view then Give settings and the image to my UIImageView and add that number to my int then i give settings and text to my UITextField and then i calculate the size of my text depending on how long is my text and the size of my font, then add that to my int and finally assign the contentSize of my ScrollView to match my int.
That way the size of your scrollview will always match your view, and the scrollView will always be at top.
But if you don't want to do all this, you can allways just:
[scrollView setContentOffset:CGPointMake(0, 0) animated:NO];
at the end of the code where you set your image and your text, and the NOto avoid the bouncing.
Hope this helps.
I have a view hierarchy like this:
UIView
- ADBannerView
- UIImageView
- UILabel
- UIButton
- UINavigationController
- UIView
I'm loading the image view, label and button from a nib file and the UINavigationController from another nib. All have autoresizing masks set. I'm creating the ADBannerView programmatically.
Now my problem is that I would like the image, label, button to move down and the navigation controller to shrink when I insert an ADBannerView. However this is not happening, instead the ADBannerView is placed on top of the image and the label.
Can anybody explain to me what am I doing wrong here?
In other to get those things to "automatically" shift down when you put in the ADBannerView, you'll need to enclose them in their own view and then change the size and position of that view. Assuming the ADBannerView is 50 pixels tall, you'll want to move that UIView down 50 pixels and reduce its height by 50 pixels.
Assuming that self.enclosingView is the new view that you will use to enclose the image, label and button... and assuming you want to make this animated (you probably do, it usually looks a lot better):
// Start the AdBannerView off of the top of the screen
CGRect adFrame = self.bannerView.frame;
adFrame.origin.x = 0.0;
adFrame.origin.y = 0.0 - adFrame.size.height;
self.bannerView.frame = adFrame;
[UIView beginAnimations:#"Show Ads" context:nil];
// Animate the shrinking of the enclosing view
CGRect enclosingFrame = self.enclosingView.frame;
enclosingFrame.size.height -= self.bannerView.frame.size.height;
enclosingFrame.origin.y += self.bannerView.frame.size.height;
self.enclosingView.frame = enclosingFrame;
// Animate the motion of the bannerView into view
adFrame.origin.y = 0.0;
self.bannerView.frame = adFrame;
[UIView commitAnimations];
Autoresizing mask defines size changes on parent's frame changes, not on sibling insertion/removal. You have to adjust frame for corresponding views programmatically. Kenny Wyland already gave you idea how this can be achieved with less pain. Take a look at CGRectDivide method - with it it's easy to split available space between two views.