什么改变了我的图层位置

Question

我有一个 TDHomeCollectionHeaderView，我在它的 initWithFrame 中设置了 zposition=-999。但是我发现 drawRect.What 中的 zPosition 是 1 发生了什么？什么改变了我的图层位置？ TDHomeCollectionHeaderView 是 UICollectionView 的 SupplementaryView。

    - (instancetype)initWithFrame:(CGRect)frame
  {
      self = [super initWithFrame:frame];
    if (self) {
        [self addSubview:self.imageView];
        [self addSubview:self.iconView];
        [self addSubview:self.label];
        self.userInteractionEnabled = NO;
        self.layer.zPosition = -999;
    }
    return self;
  }

   -(void)drawRect:(CGRect)rect
  {
   //here zposition is 1
    NSLog(@"TDHomeCollectionHeaderView %f",self.layer.zPosition);
  }

Answer 1

是雷达http://www.openradar.me/34308893. A better around is suggested in this Whosebug reply:"Set the header view layer's zPosition in willDisplaySupplementaryView".(UICollectionView fails to honour zPosition and zIndex - iOS 11 only)

什么改变了我的图层位置

What change my layer position

objective-c

z-order

layer

ios