Question

我正在使用UIView的动画功能将一条鱼的一个图像游到屏幕上，当屏幕中间已经存在一条鱼时，将它游走并开始游泳。鱼的选择是从单独的tableview控制器发送的。

为了实现这一点，我保留了UIImageView的两个实例变量，并在动画完成后为self.fishViewNext交换self.fishViewNext（参见下面的代码）。

我的问题是，在下一条鱼有机会到达之前，用户快速按下新的表格单元格。我的快速解决方案是延迟添加鱼的新消息，此刻什么都不做。这适用于2个快速触摸，但不是更多。我正在寻找想法，如果有人知道如何改进下面的代码，以便动画是平滑的，你可以点击任何最终显示的图像是最后一次点击。这里重要的方法是：

创建第一个图像视图：

- (void) createFish {

self.fishViewCurrent = [[[UIImageView alloc] init] autorelease];
self.fishViewCurrent.contentMode = UIViewContentModeScaleAspectFit;
self.fishViewCurrent.bounds = CGRectMake(0.0f, 0.0f, kFishWidth, kFishHeight);
self.fishViewCurrent.center = CGPointMake(-kFishWidth, kFishYPos); // off the screen to the left
[self addSubview:self.fishViewCurrent];

}

选择tableview单元格时调用的公共方法：

- (void) addFish:(UIImage *)fish {

if (self.fishViewNext) {
    [self performSelector:@selector(addFish:) withObject:(UIImage *)fish afterDelay:1.0];
    return;
}
self.fishViewNext = [[[UIImageView alloc] initWithImage:fish] autorelease];
self.fishViewNext.contentMode = UIViewContentModeScaleAspectFit;
self.fishViewNext.bounds = CGRectMake(0.0f, 0.0f, kFishWidth, kFishHeight);
self.fishViewNext.center = CGPointMake(self.bounds.size.width + kFishWidth, kFishYPos);  // off the screen right
[self addSubview:self.fishViewNext];

[UIView beginAnimations:@"swimFish" context:nil];
[UIView setAnimationDuration:2.0f];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[UIView setAnimationBeginsFromCurrentState:YES]; 
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(fishSwamOffHandler:finished:context:)];
[UIView setAnimationRepeatAutoreverses:NO];

self.fishViewNext.center = CGPointMake(self.center.x, kFishYPos); // center
self.fishViewCurrent.center = CGPointMake(-kFishWidth, kFishYPos);  // exit stage left

[UIView commitAnimations];   
}

处理程序将'下一个'鱼（UIImageView）切换为'当前'：

- (void)fishSwamOffHandler:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {

[self.fishViewCurrent removeFromSuperview]; 
self.fishViewCurrent = self.fishViewNext;
self.fishViewNext = nil;
}

Answer 1

最简单的方法是创建一个ivar BOOL，比如_fishIsSwimming，然后_queuedFishView然后更改addFish的开头：看起来像这样：

- (void) addFish:(UIImage *)fish 
{
    // queue the most recent fish, if one was passed in
    if(fish)    
        self.queuedFishView = [[[UIImageView alloc] initWithImage:fish] autorelease];

    // If something is swimming, leave now
    if(_fishIsSwimming)
        return;

    // If we get here and there's no queued fish, leave now
    if(!self.queuedFishView)
        return;

    // We have a queued fish and nothing is swimming, so do the queued fish next 
    // and clear the queued fish
    _fishIsSwimming = YES;
    self.nextFishView = self.queuedFishView;
    self.queuedFishView = nil;
    // Then carry on as normal
}

然后在动画完成回调中，执行以下操作：

-(void) fishSwamOffHandler:(NSString*)animationID finished:(NSNumber*)finished context:(void*)context 
{
    // We're done animating, so ready to do another swimming fish
    _fishIsSwimming = NO;

    [self.fishViewCurrent removeFromSuperview]; 
    self.fishViewCurrent = self.fishViewNext;
    self.fishViewNext = nil;

    // now call to add another fish with nil, so that it will use 
    // the queued fish if there is one and otherwise just early out
    [self addFish:nil];    
}

所以会发生的事情是你总是在queuedFishView中维护最近传入的鱼，然后一旦动画结束，你可以回到addFish，如果有一条鱼等着去，那么你发送。如果不是，您只需等待按下按钮发送的下一个

制作平滑的动画入口，退出和交换两个图像视图

1 个答案: