执行几个连续UIView动画的最佳方法？

时间：2010-10-03 10:52:08

标签： iphone uiview core-animation

我有一系列8个UIView动画，在我的视图加载后直接出现。现在，我正在使用animationDidStop:finished:context委托方法完成此任务，一切都按预期工作。问题是我为每个动画都有一个新方法。重复每个方法中的大多数代码，只有动画持续时间和元素的实际定位发生变化。

我尝试创建一个可以调用的方法，并让上下文保存适当更改UI所需的参数，但它似乎递归调用自己超过了我调用它的次数：

-(void)animationDidStop:(NSString *)animationID finished:(BOOL)finished context:(void *)context{
    NSNumber *number = (NSNumber *)context;
    int animationStep = [number intValue];
    int nextAnimationStep = animationStep + 1;
    NSNumber *nextAnimationStepNumber = [NSNumber numberWithInt:nextAnimationStep];
    NSLog(@"Animation Step: %i", animationStep);

    CGRect firstFrame = CGRectMake(self.feedsScroll.frame.size.width * 2, 0.0f, self.secondFeedView.view.frame.size.width, self.secondFeedView.view.frame.size.height);
    CGRect thirdFrame = CGRectMake(self.feedsScroll.frame.size.width * 2, 0.0f, self.thirdFeedView.view.frame.size.width, self.thirdFeedView.view.frame.size.height);

    [UIView beginAnimations:nil context:nextAnimationStepNumber];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationCurve:UIViewAnimationCurveLinear];
    [UIView setAnimationDelegate:self];

    if (animationStep < 8) 
        [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];

    NSLog(@"Beginning animations");

    switch (animationStep) {
        case 0:
            [UIView setAnimationDuration:.3];
            self.firstFeedView.view.center = CGPointMake(self.firstFeedView.view.center.x + 30, self.firstFeedView.view.center.y);
            break;
        case 1:
            [UIView setAnimationDuration:.3];
            self.firstFeedView.view.center = CGPointMake(self.firstFeedView.view.center.x  - 30, self.firstFeedView.view.center.y);
            break;
        case 2:
            [UIView setAnimationDuration:.3];
            [self.secondFeedView.view setFrame:firstFrame];
            break;
        case 3:
            [UIView setAnimationDuration:.3];
            self.secondFeedView.view.center = CGPointMake(self.secondFeedView.view.center.x + 30, self.firstFeedView.view.center.y);
            break;
        case 4:
            [UIView setAnimationDuration:.3];
            self.secondFeedView.view.center = CGPointMake(self.secondFeedView.view.center.x - 30, self.firstFeedView.view.center.y);
            break;
        case 5:
            NSLog(@"Animation step 6");
            [UIView setAnimationDuration:.5];
            self.firstFeedView.view.center = CGPointMake(self.firstFeedView.view.center.x - 230, self.firstFeedView.view.center.y);
            self.secondFeedView.view.center = CGPointMake(self.secondFeedView.view.center.x - 230, self.firstFeedView.view.center.y);
            break;
        case 6:
            [UIView setAnimationDuration:.5];
            [self.thirdFeedView.view setFrame:thirdFrame];
            break;
        case 7:
            [UIView setAnimationDuration:.3];
            self.thirdFeedView.view.center = CGPointMake(self.thirdFeedView.view.center.x + 30, self.firstFeedView.view.center.y);
            break;
        case 8:
            [UIView setAnimationDuration:.3];
            self.thirdFeedView.view.center = CGPointMake(self.thirdFeedView.view.center.x - 30, self.thirdFeedView.view.center.y);
            break;
        default:
            break;
    }

    [UIView commitAnimations];  
}

我知道这可能是一个天真的实现。我是iPhone开发的新手，我正在寻找一些适用于此的最佳实践。我是以错误的方式解决这个问题吗？

5 个答案:

答案 0 :(得分：19)

如果你愿意升级到iOS 4.0，那么新的基于块的动画方法可以使这个动画变得微不足道。例如：

[UIView animateWithDuration:1.0 animations:^{ view.position = CGPointMake(0.0f, 0.0f); } completion:^(BOOL finished){
    [UIView animateWithDuration:0.2 animations:^{ view.alpha = 0.0; } completion:^(BOOL finished){
        [view removeFromSuperview]; }];
}]

将使view在1秒的持续时间内动画显示为（0,0），淡出0.2秒，然后从其超级视图中删除。这些动画将是连续的。

+animateWithDuration:animations:completion:类方法中的第一个块包含一次性动画的属性更改，第二个块是动画完成时要执行的操作。因为此回调可以包含此类动画，所以您可以将它们嵌套以创建任意动画链。

答案 1 :(得分：16)

您可以使用块来获得非常干净的结果。

NSMutableArray* animationBlocks = [NSMutableArray new];

typedef void(^animationBlock)(BOOL);

// getNextAnimation
// removes the first block in the queue and returns it
animationBlock (^getNextAnimation)() = ^{
    animationBlock block = (animationBlock)[animationBlocks firstObject];
    if (block){
        [animationBlocks removeObjectAtIndex:0];
        return block;
    }else{
         return ^(BOOL finished){};
    }
};

//add a block to our queue
[animationBlocks addObject:^(BOOL finished){;
    [UIView animateWithDuration:1.0 animations:^{
        //...animation code...
    } completion: getNextAnimation()];
}];

//add a block to our queue
[animationBlocks addObject:^(BOOL finished){;
    [UIView animateWithDuration:1.0 animations:^{
        //...animation code...
    } completion: getNextAnimation()];
}];

//add a block to our queue
[animationBlocks addObject:^(BOOL finished){;
    NSLog(@"Multi-step Animation Complete!");
}];

// execute the first block in the queue
getNextAnimation()(YES);

取自：http://xibxor.com/objective-c/uiview-animation-without-nested-hell/

答案 2 :(得分：10)

我们使用块（CPAnimationSequence on Github）以声明方式创建了一个用于链接动画步骤的组件。我们描述了动机和理由in our iOS development blog。

它为您提供了非常易读的代码，如下所示：

[[CPAnimationSequence sequenceWithSteps:
    [CPAnimationStep           for:0.25 animate:^{ self.imageView.alpha = 0.0; }],
    [CPAnimationStep           for:0.25 animate:^{ self.headline.alpha = 0.0;  }],
    [CPAnimationStep           for:0.25 animate:^{ self.content.alpha = 0.0;   }],
    [CPAnimationStep after:1.0 for:0.25 animate:^{ self.headline.alpha = 1.0;  }],
    [CPAnimationStep           for:0.25 animate:^{ self.content.alpha = 1.0;   }],
    nil]
runAnimated:YES];

答案 3 :(得分：1)

“上下文”是一个空*，因此不予保留。有几个选择：

  • 设置时保留它。在回调开始时自动释放它。这感觉很蹩脚（Objective-C函数应该适当地保留/释放，但不幸的是上下文不是id）。
  • 将数字存储在字符串中：int animationStep = [animationID intValue];和[UIView beginAnimations:[NSString stringWithFormat:@"%d", nextAnimationStep] context:NULL];。这也感觉很蠢。
  • 假设UIKit / CoreAnimation没有取消引用指针int animationStep = (int)context;和[UIView beginAnimations:nil context:(void*)nextAnimationStep];。这很蹩脚（根据C标准可能导致未定义的行为）。

另一方面，finished:(BOOL)finished应为finished:(NSNumber*)finished。他们在原始文档中犯了一个错误;它可能更容易更改文档以反映API而不是更改API并且必须神奇地保持向后兼容性（即使传递bool更合理）。

答案 4 :(得分：-1)

 // create the view that will execute our animation
 UIImageView* logo = [[UIImageView alloc] initWithFrame:self.view.frame];
 // load all the frames of our animation
 logo.animationImages = [NSArray arrayWithObjects:  
                                 [UIImage imageNamed:@"frame_00001.png"],

                         [UIImage imageNamed:@"frame_00002.png"],
                         [UIImage imageNamed:@"frame_00003.png"],
                         [UIImage imageNamed:@"frame_00004.png"],
                                 [UIImage imageNamed:@"frame_00005"], nil];

 // all frames will execute in 3 seconds
 logo.animationDuration =3.3;
 // repeat the annimation forever
logo.animationRepeatCount = 1;
 // start animating
 [logo startAnimating];
 // add the animation view to the main window 
 [self.view addSubview:logo];
 [logo release];

将其放入ViewDidLoad

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