UIFont粗体字体和细体字体

mid字体

class func midFont(size:CGFloat) -> UIFont {
    return UIFont.init(name: "STHeitiSC-Medium", size: size)!
}

light字体

class func lightFont(size:CGFloat) -> UIFont {
    return UIFont.init(name: "STHeitiSC-Light", size: size)!
}