淡化标签文本的结尾 [英] Fade the end of a label text

问题描述

我有一个 UILabel ，我希望淡化字符串的结尾，这将超出界限。对此有什么更好的解决方案？
我应该计算标签的宽度，将它与字符串宽度进行比较，如果字符串宽度大于标签的宽度，我应该淡化最后两个字母吗？我该怎么做？
我希望这很容易。请写下你的解决方案。谢谢！
我更喜欢使用此方法计算宽度：

I have one UILabel, and i want to fade the end of the string, that is going to be out of bounds. What is the better solution for this? Should i calculate the width of the label, compare it with the string width, and if string width is bigger than label's, i should fade last two letters? How exactly should i do that? I hope it will be easy. Please write your solutions. Thanks! I prefer to use this method for calculating the width:

CGRect labelRect = [text
                    boundingRectWithSize:labelSize
                    options:NSStringDrawingUsesLineFragmentOrigin
                    attributes:@{
                     NSFontAttributeName : [UIFont systemFontOfSize:14]
                    }
                    context:nil];

推荐答案

Swift 4.0示例：

Swift 4.0 example:

    let gradient = CAGradientLayer()

    gradient.frame      = titleLabel.bounds
    gradient.colors     = [UIColor.white.cgColor, UIColor.clear.cgColor]
    gradient.startPoint = CGPoint(x: 0.1, y: 0.0)
    gradient.endPoint   = CGPoint(x: 0.95, y: 0.0)

    label.lineBreakMode = .byClipping
    label.layer.mask = gradient

结果：

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