ios 实现透明度渐变 逐渐消失效果

直接上代码
注意事项
*- (void)addMaskToMenuView:(UIView )menuView 中的menuview一定不能设置透明度为0

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor systemPinkColor];
    
    UIView *bgcView = [[UIView alloc] initWithFrame:CGRectMake(0, 100, self.view.frame.size.width, 40)];
//    bgcView.backgroundColor = UIColor.orangeColor;
    [self.view addSubview:bgcView];
    
    UIScrollView *titleScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(10, 0, self.view.frame.size.width - 60, 40)];
//    titleScrollView.backgroundColor = UIColor.greenColor;
    titleScrollView.showsHorizontalScrollIndicator = NO;
    [bgcView addSubview:titleScrollView];
    
    CGFloat buttonx = 0;
    CGFloat lineWidth = 10;
    for (NSInteger i = 0; i < 10; i++) {
        UIButton *titleButton = [[UIButton alloc] initWithFrame:CGRectMake(buttonx, 0, 50, 40)];
//        titleButton.backgroundColor = UIColor.redColor;
        [titleButton setTitle:@"123" forState:(UIControlStateNormal)];
        [titleButton setTitleColor:[UIColor blackColor] forState:(UIControlStateNormal)];
        [titleScrollView addSubview:titleButton];
        buttonx = buttonx + lineWidth + 50;
    }
    titleScrollView.contentSize = CGSizeMake(50*10+9*10+30, 40);
    
    
    [self addMaskToMenuView:bgcView];
    
    
    UIView *aaView = [[UIView alloc] initWithFrame:CGRectMake(self.view.frame.size.width - 60, 100, 60, 40)];
    aaView.backgroundColor = UIColor.blueColor;
    [self.view addSubview:aaView];
    
}

- (void)addMaskToMenuView:(UIView *)menuView {
    NSObject *transparent = (NSObject *)[UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0].CGColor;
    NSObject *opaque = (NSObject *)[UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:1.0].CGColor;
    CALayer *maskLayer = [CALayer layer];
    maskLayer.frame = menuView.bounds;
    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.frame = maskLayer.bounds;
    gradientLayer.colors = @[opaque, transparent];
    gradientLayer.locations = @[@((menuView.frame.size.width - 110) / menuView.frame.size.width),@((menuView.frame.size.width - 60) / menuView.frame.size.width)];
    gradientLayer.startPoint = CGPointMake(0, 0.5);
    gradientLayer.endPoint = CGPointMake(1, 0.5);
    [maskLayer addSublayer:gradientLayer];
    menuView.layer.mask = maskLayer;
}