Autolayout and Self-sizing UITableViewCell

I’m not going to lie.  Autolayout is a massive pain.  But.  Ultimately it’s very powerful and you’re best to just go through the pain and learn it.

Even so, you should also get a bit familiar with it, then learn about the concept of self-sizing table view cells.  It’s quite important.  Basically, as long as there is a clearly defined way for a UITableViewCell to determine its own height via the auto-layout constraints, dynamic table view cells are pretty easy.

Unfortunately, there is a lot to learn:

This series

Then this

or even Apple

Quick Reference:

How to make sure a UITableViewCell autosizes when you have a label that you want to wrap around onto multiple lines.

1. Pin the Label at top left, bottom, right.

2. Edit the right constraint to be “Greater than or Equal to”, and then set the constant to be the right-most you want to allow that (probably view margin).

3. Set that right-most constraint’s priority to 750 (high), then set (on the Label!) it’s content compression resistance priority to 749.

Should be fine now.

“Invisible Container” – HSPassthroughView

I’d like to revisit an older post which deals with allowing subviews in a view hierarchy to be touchable, but making the parent view completely “non-interactive”.

Sometimes you need a ‘container view’ that can simplify Autolayout Constraint animations.  You want the view to be ‘invisible’ whilst allowing its subviews to behave normally. Being invisible, you may also want to tell it to inherit it’s superview’s color, so to reduce the need for layer blending (better performance)

I present the updated HSPassthroughView:

#import <UIKit/UIKit.h>

IB_DESIGNABLE
@interface HSPassthroughView : UIView

@property (nonatomic, assign) IBInspectable BOOL inheritsBackgroundColor;  // defaults to NO

@end

@implementation HSPassthroughView

- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    UIView *view = [super hitTest:point withEvent:event];
    if (view == self)
    {
        NSLog(@"A view was asked for a view, but this is a QLPassthroughView.  If you see this message but expect a touch to be found, look here.");
        return nil;
    }   
    return view;  //ensure this view will never register a touch!
}
- (void)awakeFromNib
{   
    if (self.inheritsBackgroundColor && self.superview) {
        self.backgroundColor = self.superview.backgroundColor;
    }
}
- (void)willMoveToSuperview:(UIView *)newSuperview
{
    if (self.inheritsBackgroundColor) {
        self.backgroundColor = newSuperview.backgroundColor;
    }
    [super willMoveToSuperview:newSuperview];
}
@end

This helped solve a problem I had that was on StackOverflow.