传入一个label或者button，传入5s，6和6+的文字尺寸 快速定义文字大小

func isIphone6() -> Bool {

    if screenWidth() > 320 {

        return true
    }
    else {
        return false
    }
}

func isIphone6Plus() -> Bool {

    if screenWidth() > 375 {

        return true
    }
    return false
}

func fontSize(aView: UIView, fivs: CGFloat, six: CGFloat, sixPlus: CGFloat) {

    if (aView as? UILabel) != nil {

        if isIphone6Plus() {
            (aView as UILabel).font = UIFont.systemFontOfSize(sixPlus)
        }
        else if isIphone6() {
            (aView as UILabel).font = UIFont.systemFontOfSize(six)
        }
        else {
            (aView as UILabel).font = UIFont.systemFontOfSize(fivs)
        }
    }
    else if (aView as? UIButton) != nil {
        if isIphone6Plus() {
            (aView as UIButton).titleLabel!.font = UIFont.systemFontOfSize(sixPlus)
        }
        else if isIphone6() {
            (aView as UIButton).titleLabel!.font = UIFont.systemFontOfSize(six)
        }
        else {
            (aView as UIButton).titleLabel!.font = UIFont.systemFontOfSize(fivs)
        }
    }
}