我想创建一个 ImageView 对象，但是，当我使用 contentRect 属性创建时，结果有任何阴影，帮帮我。
看这段代码：
CALayer *blueLayer = [CALayer layer];
blueLayer.frame = CGRectMake(50.0f, 50.0f, 100.0f, 200.0f);
blueLayer.backgroundColor = [UIColor blueColor].CGColor;
UIImage *image = [UIImage imageNamed:@"vclrs_me_wodeshoucang"] ;
CGImageRef imageRef = image.CGImage ;
blueLayer.contents = (__bridge id _Nullable)imageRef ;
blueLayer.contentsGravity = kCAGravityCenter ;
blueLayer.contentsRect = CGRectMake(0, 0, 2, 2) ;
blueLayer.contentsScale = image.scale ;
[self.layerView.layer addSublayer:blueLayer];
并且，请阅读结果（图片）：
