如何平滑更改視圖的背景色

Question

我有10張圖像，我需要每4秒隨機更改背景顏色並進行平滑的動畫處理。

我的代碼是

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

self.bgTimer是NSTimer屬性。

改變背景的方法是

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

它會根據所選的隨機圖像更改背景，但會突然更改背景。

我需要平滑地更改顏色（更改過程需要2秒鍾，例如淡入淡出或交叉溶解）。

如何做到這一點。

還有一種更好的方法代替此NSTimer方法。

Answer 1

嘗試與此。

- (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]]];
}

要么

- (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

如果您希望通過動畫來更改顏色，請嘗試此操作。

    - (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];
        });
    });
}

如果您看動畫較慢，則增加持續時間。

Answer 3

您正在使用正確的功能，但僅需提及圖像名稱。

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

Answer 4

要停止圖像的突然更改，您需要為更改添加動畫效果-[UIView animateWithDuration: animations:]是您要的內容。 這是一個小代碼示例：

self.view.backgroundColor = [UIColor redColor];

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

顯然，您需要對其進行編輯以適合您的代碼，等等。希望對您有所幫助！

編輯：這是指向類引用的鏈接 ，以防您要閱讀有關它的信息！