iOS TableView 滚动顶部半透明效果

需要在UITableView的父视图添加半透明遮罩

    // 渐变图层
    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.frame = self.view.frame;

    // 设置颜色
    gradientLayer.colors = @[(id)[[UIColor blackColor] colorWithAlphaComponent:0.0f].CGColor,
                             (id)[[UIColor blackColor] colorWithAlphaComponent:1.0f].CGColor];
    gradientLayer.locations = @[ @0, @0.15, @1];

    // 添加渐变图层
    self.view.layer.mask = gradientLayer;

// 渐变图层

CAGradientLayer *gradientLayer = [CAGradientLayer layer];

gradientLayer.frame = self.view.frame;

// 设置颜色

gradientLayer.colors = @[(id)[[UIColor blackColor] colorWithAlphaComponent:0.0f].CGColor,

(id)[[UIColor blackColor] colorWithAlphaComponent:1.0f].CGColor];

gradientLayer.locations = @[ @0, @0.15, @1];

// 添加渐变图层

self.view.layer.mask = gradientLayer;