I have finally been able to get my app updated with constraints and Autolayout. However, now I'm having some weird behavior. My app flips over to a page where I have my settings, but when I return the pagination in the scroll view is wacky. It looks like it gets stuck between pages upon firing viewWillAppear. I had it log the contentOffset. When the bug occurs, it actually reports the offset to be 0.000000 when it has not yet scrolled all the way back. Any thoughts?
Ok, I've found a hacky workaround to resolve my problem. I still do not install the core issue.
Basically, I just revert the changes made to center of my contentView.
- (void)viewDidLoad
{
[super viewDidLoad];
[_contentView addObserver:self forKeyPath:#"center" options:NSKeyValueObservingOptionNew context:nil];
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
if (object == _contentView && [keyPath isEqualToString:#"center"]) {
if (!_ignoreNextChange) {
_ignoreNextChange = YES;
_contentView.frame = CGRectMake(0, 0, _contentView.frame.size.width, _contentView.frame.size.height);
}
_ignoreNextChange = NO;
}
}
Well, at long last I decided to set a variable to be the UIScrollView offset on scrollViewDidEndDecelerating and return to it on viewWillAppear. I still have a problem with the images in the ScrollView, but I attribute that to the constraints at this point.
Related
I'm trying to implement a custom UICollectionView that shows all elements from the asset library. While displaying the items is not that big of a deal, I run into a weird bug which I think has to do something with the layout I'm using.
Let's start with some screenshots to indicate what's going on. I'll just post the links to these images to be easy on your scroll wheels :-)
1. Initial
https://dl.dropboxusercontent.com/u/607872/stackoverflow/01-uicollectionview-start.png
Everything ok.
2. Scrolled down
https://dl.dropboxusercontent.com/u/607872/stackoverflow/02-uicollectionview-scrolleddown.png
The images from the first row (which isn't visible anymore) repeat behind the images in the last row. The first one is invisible because it is entirely overlapped.
3. Scrolled up again
https://dl.dropboxusercontent.com/u/607872/stackoverflow/03-uicollectionview-scrollup.png
The first image (in the background) is from the same row, but should be the third. The 2nd and 3rd image are from the last row.
Here's some code. I hope I didn't miss any relevant stuff - if so, please let me know.
MultiImagePickerController.m (:UICollectionViewController, protocols: UICollectionViewDataSource, UICollectionViewDelegateFlowLayout)
- (void)loadView {
[...] // layout stuff
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
[layout setScrollDirection:UICollectionViewScrollDirectionVertical];
_collectionView = [[UICollectionView alloc] initWithFrame:collectionRect collectionViewLayout:layout];
[_collectionView setDataSource:self];
[_collectionView setDelegate:self];
[_collectionView registerClass:[MultiImagePickerCell class] forCellWithReuseIdentifier:#"MultiImagePickerCellIdentifier"];
[_collectionView setBackgroundColor:[UIColor whiteColor]];
[self.view addSubview:_collectionView];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
MultiImagePickerCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"MultiImagePickerCellIdentifier" forIndexPath:indexPath];
if ( !cell ) {
CGSize sizeCell = [MultiImagePickerCell defaultSize];
cell = [[MultiImagePickerCell alloc] initWithFrame:CGRectMake( 0, 0, sizeCell.width, sizeCell.height )];
}
NSString *groupname = [self getKeyFromMutableDictionary:assetList forIndex:indexPath.section];
[cell addImageUsingAsset:[[assetList objectForKey:groupname] objectAtIndex:indexPath.row]];
return cell;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
CGSize sizeCell = [MultiImagePickerCell defaultSize];
return CGSizeMake( sizeCell.width + 10.0, sizeCell.height + 10.0 );
}
MultiImagePickerCell - (void)addImageUsingAsset:(ALAsset *)asset;
This method adds a UIImageView and a UIImage to the cell to show the asset. Nothing special, in my opinion. When I set breakpoints in cellForItemAtIndexPath, I can see that the correct asset is being read from the assetList and the views are calculated correctly. The drawRect method of the cell is NOT implemented.
I think I experienced the same problem a few years back when I tried to programmatically create a UITableViewController, but I can't remember how I solved it.
Any suggestions?
Got it - I had to remove the subviews from my cells.
I was wondering how to swipe the ViewController with a visible keyboard?
in iOS 7 I can swipe the ViewController from side to side, but the keyboard stays put.
in short, I would like to get to the following state:
Thanks!
Update:
I can't recommend the original solution. While it performed well (when it performed at all), it was an unreliable hack, and could easily break the pop gesture recognizer.
My colleague Dave Lyon came up with a great solution using iOS 7 view controller transitions and packaged it up into a pod:
https://github.com/cotap/TAPKeyboardPop
Once installed, just import the main file and you should be good to go.
Original:
I'd love to know if there's a better way of doing this, but I was able to achieve the behavior by adding the keyboard's view as a subview of the view controller's main view:
- (void)viewDidLoad
{
[super viewDidLoad];
self.textView.inputAccessoryView = [UIView new];
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center addObserver:self
selector:#selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
- (void)keyboardWillHide:(NSNotification *)note
{
if (self.textView.isFirstResponder) {
UIView *keyboardView = self.textView.inputAccessoryView.superview;
if (keyboardView) {
dispatch_async(dispatch_get_main_queue(), ^{
[self.view addSubview:keyboardView];
});
}
}
}
I've found you can also animate the keyboard with the gesture (via addTarget:action:), but the performance is abysmal and doesn't cleanly animate if the gesture is prematurely canceled.
I have a Mac app that's using IKImageBrowserView. I've subclassed IKImageBrowserView and I'm returning a custom cell type from newCellForRepresentedItem.
In my cell, I'm creating and returning a layer from layerForType:
// When asked for a foreground layer, return a new layer that we'll render the icon decorations into
- (CALayer *)layerForType:(NSString *)type {
if ([type isEqualToString:IKImageBrowserCellForegroundLayer]) {
#synchronized(self) {
if (!self.foregroundLayer) {
self.foregroundLayer = [[CALayer alloc] init];
self.foregroundLayer.delegate = self;
self.foregroundLayer.needsDisplayOnBoundsChange = YES;
[self.foregroundLayer setNeedsDisplay];
}
}
return self.foregroundLayer;
} else {
return [super layerForType:type];
}
}
I have my cell observing an object, and calling setNeedsDisplay on my custom layer when it changes.
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
self.percentDone = (float)self.bytesSoFar/self.bytesTotal;
NSLog(#"Update");
[self.foregroundLayer setNeedsDisplay];
}];
}
Here's the problem I'm having: The download proceeds, the object being observed fires the observer (so observeValueForKeyPath is called) and setNeedsDisplay is called. I verified this by logging with NSLog messages.
But the drawing method:
- (void)drawLayer:(CALayer *)theLayer
inContext:(CGContextRef)theContext
{
NSLog(#"Drawing");
// Drawing happens here
}
What I'm seeing is that the drawing starts out okay - printing "Update" and "Drawing" interleaved - but after a short time, the "Drawing" stops and just the "Update" messages continue.
If I click in the image browser, or tap a key on the keyboard, the "Drawing" resumes for a short while, and then stops, back to just "Update".
It's like I need to trigger a repaint using the keyboard or mouse - the setNeedsDisplay isn't doing it - but I don't understand why. It does work for a short time, stops working, then only works while I'm providing mouse input.
This has me baffled. I'd appreciate any suggestions.
I didn't find the problem here, but I did find a solution.
Invalidating IKImageBrowserView cells doesn't cause them to be repainted because IKImageBrowserView, probably for performance, doesn't redraw cells unless their version changes.
Instead of invalidating the cell, I now increment the imageVersion returned by my IKImageBrowserItem, and then invalidate the IKImageBrowserView. This reliably redraws the item.
I have a webview which I would like to remove the elasticity from. As it is now, when scrolling a page that is smaller than the webview, it will make an elasticity effect revealing the background underneath. I would like to remove this.
I have tried doing the following but without success. It finds the WebDynamicScrollBarsView but setting the elasticity of this, does not change anything.
- (void)awakeFromNib
{
NSScrollView *scrollView = [self findScrollViewInSubviews:self.subviews];
scrollView.horizontalScrollElasticity = NSScrollElasticityNone;
scrollView.verticalScrollElasticity = NSScrollElasticityNone;
}
- (NSScrollView *)findScrollViewInSubviews:(NSArray *)subviews
{
for (NSView *view in subviews)
{
if ([view isKindOfClass:[NSScrollView class]])
return (NSScrollView *) view;
else
return [self findScrollViewInSubviews:view.subviews];
}
return nil;
}
Does anyone know how to remove the elasticity effect from a webview?
In my subclass of WebView (or you can just do it directly, with webView.mainFrame.frameView.documentView.enclosingScrollView, but this makes it easier for me, personally)
// return the scroll view that we are currently using, if applicatble
- (NSScrollView *)mainScrollView {
return [[[[self mainFrame] frameView] documentView] enclosingScrollView]; // can be nil
}
Then on finish load, as Anne noted literally as I was typing my answer :) ,
- (void)webView:(WebView *)sender didFinishLoadForFrame:(WebFrame *)frame {
NSScrollView *mainScrollView = [sender mainScrollView];
[mainScrollView setVerticalScrollElasticity:NSScrollElasticityNone];
[mainScrollView setHorizontalScrollElasticity:NSScrollElasticityNone];
}
I'm not sure if doing it after the content has loaded is necessary, but I don't have my mac with me to try right now.
I have a detail view, and when viewdidload in detailviewcontroller, MPMoviePlayerController allocs and plays an audio, but even if I navigate backto main table, audio is still being played.
How can I stop MPMovieplayercontroller when I navigate back to main table ? This is my MPMoviePlayerController code:
.h
MPMoviePlayerController *player;
.m
- (void)viewDidLoad
{
[super viewDidLoad];
//Get the Movie
NSURL *movieURL = [NSURL URLWithString:#"some link"];
player = [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
//Place it in subview, else it won’t work
player.view.frame = CGRectMake(20, 20, 280, 25);
player.backgroundView.backgroundColor = [UIColor clearColor];
[self.view addSubview:player.view];
// Play the movie.
[player play];
}
I even added following code into viewdidunload method, but didn't work.
- (void)viewDidUnload {
[player stop];
player.initialPlaybackTime = -1;
[player release];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
What do you guys suggest ?
Thanks in advance,
I liked the user experience of viewDidDisappear better than viewWillDisappear. The animation starts and the movie stops after - the audio flows better for me this way.
-(void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
[_moviePlayer stop];
}
I am having a similar issue. I am unable to use "viewDidDisappear" or "viewWillDisappear" because I have a "config" type view that can be opened while the content is playing, and it will trigger those two methods.
EDIT: Found that viewDidUnload and viewWillUnload are not getting called any more (I'm currently on an iOS 6+ device)...
From the documentation:
Availability: iOS (3.0 and later) Deprecated: Views are no longer
purged under low-memory conditions and so this method is never called.
I just created a simple function called unload, and inside the function, set any objects I needed to = nil (I'm using ARC). At the time that I make the call to remove the view, I call the unload function as well. Hope it helps someone.