Objective-C：如何编写连续的一系列事件

Question

Objective-C让我有点疯狂。我知道它不是一种能够一个接一个地处理每个命令的语言，但如果我需要这样做呢？

例如，我的问题是我想：

1. 截取当前iPhone屏幕的截图
2. 在将此屏幕截图添加到我的屏幕之前，我想添加另一个视图
3. 然后添加屏幕截图，以便其他视图为HIDDEN BENEATH
4. 然后有一个动画，将屏幕截图滑出视图并显示什么是HIDDEN BENEATH

现在，应用程序将截取方法中添加的所有视图的屏幕截图（完全忽略我的事件顺序），并且不会隐藏添加的视图BENEATH我的屏幕截图。无论我尝试做什么，一切都会立即发生，这很糟糕。

这是我的代码：

- (void)takeScreenShot
{
    screenShotView = [[UIImageView alloc] initWithImage:[self screenshot]];
    [screenShotView setFrame:CGRectMake(0, -20, 320, 480)];

    accessoryView.hidden = YES;
    [self.view addSubview:accessoryView]; // which is hidden beneath and about to be revealed
    [self.view addSubview:screenShotView];

    [self.view bringSubviewToFront:screenShotView];

    [self startAnimation];
}

- (void)startAnimation
{
    [UIView animateWithDuration:0.0
                          delay:0
                        options:UIViewAnimationOptionCurveEaseIn
                     animations:^{

                         accessoryView.hidden = NO;

                     }
                     completion:^(BOOL finished){
                         [UIView animateWithDuration:3.0
                                               delay:0
                                             options:UIViewAnimationOptionCurveLinear
                                          animations:^{
                                              screenShotView.transform = CGAffineTransformMakeTranslation(-320, 0);   
                                          }
                                          completion:^(BOOL finished){                                        
                                          }
                          ];    
                     }];
}



- (UIImage*)screenshot 
{
    // Create a graphics context with the target size
    // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
    // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
    CGSize imageSize = [[UIScreen mainScreen] bounds].size;
    if (NULL != UIGraphicsBeginImageContextWithOptions)
        UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    else
        UIGraphicsBeginImageContext(imageSize);

    CGContextRef context = UIGraphicsGetCurrentContext();

    // Iterate over every window from back to front
    for (UIWindow *window in [[UIApplication sharedApplication] windows]) 
    {
        if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen])
        {
            // -renderInContext: renders in the coordinate space of the layer,
            // so we must first apply the layer's geometry to the graphics context
            CGContextSaveGState(context);
            // Center the context around the window's anchor point
            CGContextTranslateCTM(context, [window center].x, [window center].y);
            // Apply the window's transform about the anchor point
            CGContextConcatCTM(context, [window transform]);
            // Offset by the portion of the bounds left of and above the anchor point
            CGContextTranslateCTM(context,
                                  -[window bounds].size.width * [[window layer] anchorPoint].x,
                                  -[window bounds].size.height * [[window layer] anchorPoint].y);

            // Render the layer hierarchy to the current context
            [[window layer] renderInContext:context];

            // Restore the context
            CGContextRestoreGState(context);
        }
    }

    // Retrieve the screenshot image
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;
}

Answer 1

这不是真正的答案，但评论没有提供足够的空间。

我刚刚重新创建了一个简单的项目，看看添加视图的顺序是否与截图有任何区别。

我使用了基于视图的应用程序模板。笔尖有两个按钮，连接到属性btn1和btn2。请参见屏幕截图1.上方按钮btn1连接到一个动作，开始拍摄屏幕截图并将其添加到按钮下方以查看差异。第二个按钮最初是隐藏的。

截屏1

这是我的viewController代码。 myView是您的附件视图，将在viewWillAppear上创建。此视图包含一个标签，稍后您将看到。

标题

...

@interface ScreenshotviewsViewController : UIViewController 
{
    UIButton *btn1;
    UIButton *btn2;

    UIView *myView;
}

@property (nonatomic ,retain) IBOutlet UIButton *btn1;
@property (nonatomic ,retain) IBOutlet UIButton *btn2;
@property (nonatomic ,retain) UIView *myView;

- (IBAction)doTheThings;

@end

我会跳过你的截图方法：没有任何改变，就像一个魅力:)。结果屏幕截图2

• 截屏
• show btn2
• 将myView添加为子视图
• 将截屏添加为子视图

如您所见，屏幕截图未显示其他视图。我只是将它添加到按钮下方以查看差异。

实施：案例1

- (void)viewWillAppear:(BOOL)animated
{
    self.myView = [[[UIView alloc] initWithFrame:CGRectMake(0, 20, 320, 50)] autorelease];

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(5, 5, 200, 40)];
    myView.backgroundColor = [UIColor greenColor];
    [myView addSubview:label];

    label.text = @"fooo";

    [label release];
}

- (IBAction)doTheThings
{
    UIImageView *screenShotView = [[UIImageView alloc] initWithImage:[self screenshot]];
    [screenShotView setFrame:CGRectMake(0, 230, 320, 480)];

    btn2.hidden = NO;

    [self.view addSubview:myView];
    [self.view addSubview:screenShotView];
    [screenShotView release];
}

截屏2

案例二将是

• show btn2
• 将myView添加为子视图
• 截屏

• 将截屏添加为子视图

  • （IBAction为）doTheThings { btn2.hidden = NO; [self.view addSubview：myView];

    UIImageView * screenShotView = [[UIImageView alloc] initWithImage：[self screenshot]]; [screenShotView setFrame：CGRectMake（0,230,320,480）];

    [self.view addSubview：screenShotView]; [screenShotView发布]; }

截屏3

如您所见，订单已被识别。我已经省略了动画。删除动画，看看是否有效。否则像我一样在一个单独的项目中尝试这个，看看它是否孤立地工作。如果是的话，我们将不得不深入了解你的应用程序。