iOS 11 下 UICollectionView 的HeaderView 遮挡滚动条

这个问题在之前的 iOS 10 上是没有的，iOS 11 新出之后才出现。在使用了- collectionView: viewForSupplementaryElementOfKind: atIndexPath:的 UICollectionView 页面中，滑动页面的时候滚动条会被 HeaderView 遮挡.

#import "CustomCollectionReusableView.h"

#ifdef __IPHONE_11_0

@interface CustomLayer : CALayer

@end

#endif

@interface CustomCollectionReusableView ()

@property (nonatomic, strong) UILabel *showLabel;

/**< 显示控件 */

@end

#ifdef __IPHONE_11_0

@implementation CustomLayer - (CGFloat) zPosition { return 0; }

@end

#endif

@implementation CustomCollectionReusableView

- (void)layoutSubviews {

[super layoutSubviews];

[self _setUpSubViews];

}

- (void)_setUpSubViews {

[self addSubview:self.showLabel];

}

#pragma mark - Lazy

- (UILabel *)showLabel{

if (!_showLabel) {

_showLabel = [[UILabel alloc] initWithFrame:CGRectMake(20, 20, 120, self.frame.size.height)];

_showLabel.font = [UIFont systemFontOfSize:13];

_showLabel.textAlignment = NSTextAlignmentLeft;

_showLabel.backgroundColor = [UIColor clearColor];

_showLabel.textColor = [UIColor redColor]; } return _showLabel;

}

#ifdef __IPHONE_11_0

+ (Class)layerClass {

return [CustomLayer class];

}

#endif

@end