ios – 在xCode中创建类似于Solar Weather Application的动画渐变背景

>将CAGradientLayer添加到视图控制器(或自定义视图)中,例如：

@property (nonatomic,retain) CAGradientLayer *gradient;

>在视图控制器中,在viewDidLoad中,创建并添加渐变图层到您的视图：

self.gradient = [CAGradientLayer layer];
gradient.frame = self.view.bounds;
gradient.colors = [NSArray arrayWithObjects:
               (id)topColor.CGColor,(id)bottomColor.CGColor,nil];
gradient.locations = [NSArray arrayWithObjects:
                  [NSNumber numberWithFloat:0.0f],[NSNumber numberWithFloat:0.7],nil];
[self.view.layer addSublayer:self.gradient];

3A.添加一个NSTimer到您的控制器将通过执行以适当的时间间隔更新self.gradient：

topColor = ...; bottomColor = ...;
  NSArray* newColors = [NSArray arrayWithObjects:
                 (id)topColor.CGColor,nil];
 [(CAGradientLayer *)self.layer setColors:newColors];

这将允许您在每个步骤中准确地确定要用于渐变的颜色.否则,您可以尝试使用动画,如下所示：

3B.添加这样的动画,

- (void)animateLayer... {

  [UIView animateWithDuration:duration 
                        delay:0
                      options:UIViewAnimationOptionCurveEaseInOut
                   animations:^{
    [CATransaction begin];
    [CATransaction setAnimationDuration:duration];

      topColor = ...; bottomColor = ...;
      NSArray* newColors = [NSArray arrayWithObjects:
                 (id)topColor.CGColor,nil];
     [(CAGradientLayer *)self.layer setColors:newColors];

     [CATransaction commit];
  }
          completion:^(BOOL b) {
              [self animateLayer..];
          }];
}

您也可以组合3a和3b.