NSTextField 没有ios UILabel那么灵活可以自动换行，所有自己写了个方法，可以宽度自适应，上代码

func fitFontSize(maxSize : NSSize = NSSize.zero){
        var text = self.stringValue
        var newSize = NSSize.zero
        self.sizeToFit()
        newSize = self.size
        var width = newSize.width;
        var height = newSize.height;
        let characterSize = width/CGFloat(text.count)
        if maxSize.width > 0{
            if width > maxSize.width{
                width = maxSize.width
                var count = Int(maxSize.width / characterSize)
                var array = text.components(separatedBy: " ")
                var newString = ""
                var heightCount = 1;
                if array.count > 1{
                    var currentCount = 0
                    for i in 0..<array.count{
                        if currentCount + array[i].count > count{
                            newString += "\n"
                            heightCount += 1;
                            currentCount = 0
                        }
                        newString += array[i] + " "
                        currentCount += array[i].count + 1
                    }
                    text = newString
                }else{
                    while count < text.count{
                        text.insert("\n", at: String.Index.init(encodedOffset: count))
                        count += count + 1
                    }
                }
                height = height * CGFloat(heightCount)
            }
        }
        self.stringValue = text
        self.size = NSSize(width: width, height: height)
    }

传入固定宽度，自适应后的宽度大于固定宽度会自动换行，并调整高度。
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