Question

我有10张图片，我需要每4秒随机更改一次背景颜色，并保持平滑动画。

我的代码是

self.bgTimer = [NSTimer scheduledTimerWithTimeInterval: 4.0 target: self
                        selector: @selector(updateViewBackground)
                        userInfo: nil repeats: YES];

self.bgTimer是NSTimer属性。

和更改背景的方法是

- (void)updateViewBackground {
int randomNumber = arc4random_uniform(10);
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:[NSString stringWithFormat:@"random_bg_%i",randomNumber]]];
}

根据所选的随机图像改变背景，但它会突然改变背景。

我需要平滑地改变颜色（改变就像褪色或交叉溶解需要2秒）。

如何实现这一点。

并且还有一种更好的方法来代替这种NSTimer方法。

Answer 1

试试这个......

- (void)updateViewBackground {
    CATransition *animation = [CATransition animation];
    [animation setDelegate:self];
    [animation setType:kCATransitionFromBottom];
    [animation setDuration:1.0];
    [animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
    [[self.view layer] addAnimation:animation forKey:@"transitionViewAnimation"];
    int randomNumber = arc4random_uniform(10);
    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:[NSString stringWithFormat:@"random_bg_%i",randomNumber]]];
}

或

- (void)updateViewBackground { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.3]; int randomNumber = arc4random_uniform(10); self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:[NSString stringWithFormat:@"random_bg_%i",randomNumber]]]; [UIView commitAnimations]; }

Answer 2

如果您希望使用类似动画来更改颜色，请尝试此操作。

    - (void)updateViewBackground {
    int randomNumber = arc4random_uniform(10);
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,  0ul);
    dispatch_async(queue, ^{
        dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
            [UIView transitionWithView:self.view duration:7.25 options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
                self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:[NSString stringWithFormat:@"random_bg_%i",randomNumber]]];
            } completion:nil];
        });
    });
}

如果你看动画更慢，那就增加持续时间。

Answer 3

您正在使用正确的功能，但只需提及图像名称。

- (void)updateViewBackground  {
    int randomNumber = arc4random_uniform(10);
    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:[NSString stringWithFormat:@"random_bg_%i.png",randomNumber]]];
}

Answer 4

要停止图像突然改变，您需要为更改设置动画-[UIView animateWithDuration: animations:]正是您正在寻找的。这是一个小代码示例：

self.view.backgroundColor = [UIColor redColor];

[UIView animateWithDuration:1.0 animations ^{
    self.view.backgroundColor = [UIColor greenColor];
}];

显然你需要编辑它以适合你的代码等。希望它有所帮助！

编辑：如果你想阅读它，请参阅课程参考a link！

如何顺利改变视图的背景颜色

4 个答案: