ios - CALayer 的图像未显示

我正在尝试使用 CALayer 显示图像，但图像未显示。我已经验证了 'image' 不是 nil，image.size 是正确的，并且 layer.contents 是一个有效的 CABackingStore。

- (void)viewDidLoad
{
  [super viewDidLoad];

  layer = [[CALayer alloc] init];
  [self.view.layer addSublayer:layer];
  UIImage *image = [UIImage imageNamed"download.jpeg"];
  layer.bounds = CGRectMake(0, 0, image.size.width, image.size.height);
  layer.position = self.view.center;
  layer.contents = (id)image.CGImage;

  [layer setNeedsDisplay];
}

这可能是什么问题？

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Best Answer-推荐答案

删除 [layer setNeedsDisplay]; 应该会纠正这种行为。

来自 docs (强调):

Calling this method causes the layer to recache its content. This results in the layer potentially calling either the displayLayer: or drawLayer:inContext: method of its delegate. The existing content in the layer’s contents property is removed to make way for the new content.

关于ios - CALayer 的图像未显示，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17930454/