是否有uiview调整大小事件?

layoutSubviews

bounds When does an associated object get released?

[yourView addObserver:self forKeyPath:@"bounds" options:0 context:nil];

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (object == yourView && [keyPath isEqualToString:@"bounds"]) {
        // do your stuff, or better schedule to run later using performSelector:withObject:afterDuration:
    }
}

UIView

override var bounds: CGRect {
    didSet {
        // ...
    }
}

var boundsObservation: NSKeyValueObservation?

func beginObservingBounds() {
    boundsObservation = observe(\.bounds) { capturedSelf, _ in
        // ...
    }
}

-(void)setBounds:(CGRect)newBounds {
    BOOL const isResize = !CGSizeEqualToSize(newBounds.size, self.bounds.size);
    if (isResize) [self prepareToResizeTo:newBounds.size]; // probably saves 
    [super setBounds:newBounds];
    if (isResize) [self recoverFromResizing];
}

setFrame: frame center bounds transform

private var observer: NSKeyValueObservation?

override func viewDidLoad() {
    super.viewDidLoad()
    observer = view.layer.observe(\.bounds) { object, _ in
        print(object.bounds)
    }
    // ...
}
override func viewWillDisappear(_ animated: Bool) {
    observer?.invalidate()
    //...
}

- (void) setFrame:(CGRect)frame
{
  // Call the parent class to move the view
  [super setFrame:frame];

  // Do your custom code here.
}

viewDidLayoutSubviews

override func viewDidLayoutSubviews() {
    // update subviews
}