Better Solution:
The issue is when the UITableView changes the height of a cell, most likely from -beginUpdates and -endUpdates. Prior to iOS 10 an animation on the cell would take place for both the size and the origin. Now, in iOS 10 GM, the cell will immediately change to the new height and then will animate to the correct offset.
The solution is pretty simple with constraints. Create a guide constraint which will update it's height and have the other views which need to be constrained to the bottom of the cell, now constrained to this guide.
- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
if (self) {
UIView *heightGuide = [[UIView alloc] init];
heightGuide.translatesAutoresizingMaskIntoConstraints = NO;
[self.contentView addSubview:heightGuide];
[heightGuide addConstraint:({
self.heightGuideConstraint = [NSLayoutConstraint constraintWithItem:heightGuide attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0f constant:0.0f];
})];
[self.contentView addConstraint:({
[NSLayoutConstraint constraintWithItem:heightGuide attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.contentView attribute:NSLayoutAttributeTop multiplier:1.0f constant:0.0f];
})];
UIView *anotherView = [[UIView alloc] init];
anotherView.translatesAutoresizingMaskIntoConstraints = NO;
anotherView.backgroundColor = [UIColor redColor];
[self.contentView addSubview:anotherView];
[anotherView addConstraint:({
[NSLayoutConstraint constraintWithItem:anotherView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0f constant:20.0f];
})];
[self.contentView addConstraint:({
[NSLayoutConstraint constraintWithItem:anotherView attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:self.contentView attribute:NSLayoutAttributeLeft multiplier:1.0f constant:0.0f];
})];
[self.contentView addConstraint:({
// This is our constraint that used to be attached to self.contentView
[NSLayoutConstraint constraintWithItem:anotherView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:heightGuide attribute:NSLayoutAttributeBottom multiplier:1.0f constant:0.0f];
})];
[self.contentView addConstraint:({
[NSLayoutConstraint constraintWithItem:anotherView attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:self.contentView attribute:NSLayoutAttributeRight multiplier:1.0f constant:0.0f];
})];
}
return self;
}
Then update the guides height when needed.
- (void)setFrame:(CGRect)frame {
[super setFrame:frame];
if (self.window) {
[UIView animateWithDuration:0.3 animations:^{
self.heightGuideConstraint.constant = frame.size.height;
[self.contentView layoutIfNeeded];
}];
} else {
self.heightGuideConstraint.constant = frame.size.height;
}
}
Note that putting the update guide in -setFrame: might not be the best place. As of now I have only built this demo code to create a solution. Once I finish updating my code with the final solution, if I find a better place to put it I will edit.
Original Answer:
With the iOS 10 beta nearing completion, hopefully this issue will be resolved in the next release. There's also an open bug report.
My solution involves dropping to the layer's CAAnimation. This will detect the change in height and automatically animate, just like using a CALayer unlinked to a UIView.
The first step is to adjust what happens when the layer detects a change. This code has to be in the subclass of your view. That view has to be a subview of your tableViewCell.contentView. In the code, we check if the view's layer's actions property has the key of our animation. If not just call super.
- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event {
return [layer.actions objectForKey:event] ?: [super actionForLayer:layer forKey:event];
}
Next you want to add the animation to the actions property. You might find this code is best applied after the view is on the window and laid out. Applying it beforehand might lead to an animation as the view moves to the window.
- (void)didMoveToWindow {
[super didMoveToWindow];
if (self.window) {
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"bounds"];
self.layer.actions = @{animation.keyPath:animation};
}
}
And that's it! No need to apply an animation.duration since the table view's -beginUpdates and -endUpdates overrides it. In general if you use this trick as a hassle-free way of applying animations, you will want to add an animation.duration and maybe also an animation.timingFunction.
