Question

尝试从KVO观察中调用此消息。下载图像后，将发送此消息。完成块中的消息还包含一个正常工作的动画（动画正确）。此动画应用没有动画发生的变换（等待动画的长度，然后跳转到最终状态）。

/**
 *  Discover the subview with the supplied tag, attach the fullsize image to the view
 *  scale to fullsize and begin retract.
 *  @param viewTag int - #FUTURE USE# - The tag of the view to be animated.
 *  @param image UIImage - #FUTURE USE# - The image to be applied to the view.
 *  @return void
 */
- (void)animateViewWithTag:(int)viewTag andImage:(UIImage *)image {

    Panel *activePanel = [self.panels objectAtIndex:currentIndex];
    UIView *activePanelView = [self.view viewWithTag:activePanel.panelId];

    // Display the transition to the fullsize version of the panel image.
    // Determine the scale that needs to be applied to the view to show
    // the image in the appropriate scaling. If scaled image is greater than
    // the size of the screen, find the best fit.

    float scale = image.size.width / activePanelView.frame.size.width;

    if (image.size.width > self.view.window.frame.size.width || image.size.height > self.view.window.frame.size.height) {
        // The image will scale beyond the bounds of the window, scale must be adjusted.
        scale = self.view.window.frame.size.width / activePanelView.frame.size.width;
    }

    CGAffineTransform transform = CGAffineTransformMakeScale(scale, scale);

    [UIView animateWithDuration:1.0
                     animations:^{
                         // Get the fullsize image and display it in the growing panel.
                         [activePanelView setTransform:transform];
                         [NSThread sleepForTimeInterval:3.0];
                     } 
                     completion:^(BOOL finished) {
                         [self retractImage:activePanelView];
                     }];
}


#pragma mark - KVO

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {       
    int tmpInt = (int)context;        
    UIImage *tmpImage = [change objectForKey:NSKeyValueChangeNewKey];

    if ( keyPath == @"imgOriginal" ) {
        [self animateViewWithTag:[(Panel *)object panelId] andImage:tmpImage];             
    }   

}

Answer 1

线程睡眠的目的是什么？

如果让主线程处于睡眠状态，那么它不会在此期间更新动画。

如果你没有在主线程上调用它，那么它也不会起作用，因为UIKit动画不是线程安全的，只能从主线程中可靠地使用。

UIView animateWithDuration：动画：完成：应用变换，而不是动画

1 个答案: