如何知道UIView是調整到內側還是外側？

Question

如何知道UIView正在調整大小並且框架正在增加或減少（或內側或外側）？

例如，我有一個UIImageView（我正在使用第三方library來調整對象的大小）。它的當前框架是（someX，someY，200,50），現在如果我以某種方式調整寬度，它將寬度更改爲300，在另一種情況下，它將其更改爲150.我應該知道它的增加/減少。

Answer 1

我能夠做到這樣，

添加上述庫（SPUserResizableView.h）自定義委託，- (void)userResizableViewIsResizing:(SPUserResizableView *)userResizableView {}

- (void)userResizableViewIsResizing:(SPUserResizableView *)userResizableView { 
    id contentView = userResizableView.contentView; 
    if([contentView isKindOfClass:[iOTextField class]]) { 
     iOTextField *textField = (iOTextField *)contentView;   
     if([self isResizingUpWithOriginalSize:textField.referenceiOProperties.originalSize currentSize:userResizableView.frame.size withiOTextField:textField]) { 
      [textField increaseFont]; 
     } else { 
      [textField decreaseFont]; 
     } 
    } 
} 

- (BOOL) isResizingUpWithOriginalSize:(CGSize)original currentSize:(CGSize)currentSize withiOTextField:(iOTextField *)textField { 
    CGFloat width = (currentSize.width - original.width); 
    CGFloat height = (currentSize.height - original.height); 
    if(width <= 0.0f && height <= 0.0f) { 
     textField.lastWidth = width; 
     textField.lastHeight = height; 
     return NO; 
    } else if(width > textField.lastWidth) { 
     if(textField.lastWidth <= 0.0f) { 
      textField.lastWidth = width; 
      textField.lastHeight = height; 
      return NO; 
     } 
     textField.lastWidth = width; 
     textField.lastHeight = height; 
     return YES; 
    } else if(height > textField.lastHeight) { 
     if(textField.lastHeight <= 0.0f) { 
      textField.lastWidth = width; 
      textField.lastHeight = height; 
      return NO; 
     } 
     textField.lastWidth = width; 
     textField.lastHeight = height; 
     return YES; 
    } else { 
     textField.lastWidth = width; 
     textField.lastHeight = height; 
     return NO; 
    } 
} 

在SPUserResizableView.m課上對此觸摸事件做一些小改動。

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {  
    if(self.delegate && [self.delegate respondsToSelector:@selector(userResizableViewIsResizing:)]) { 
     [self.delegate userResizableViewIsResizing:self]; 
    } 
} 

Answer 2

你可以做一些Key-Value Observing。例如，如果你的UIImageView *imageView，那麼你可以：

[imageView addObserver:self forKeyPath:@"frame" options:0 context:NULL]; 

您還需要實現這個方法，以應對變化：

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context 
{ 
    UIImageView *imageView = (UIImageView *)object; 
    // Do what you gotta do, like save the current size in 
    // an instance variable so you can compare and see increase/decrease in size 
}