// 得到字符串的高度

func getTextHeight(text :String,width: CGFloat,fontSize :CGFloat = 14) -> CGFloat {

let textNormal = text as NSString

let size = CGSizeMake(width, 1000)

let font = UIFont.systemFontOfSize(fontSize)

let dic = NSDictionary(object: font , forKey: NSFontAttributeName)

let strSize = textNormal.boundingRectWithSize(size, options: .UsesLineFragmentOrigin , attributes: dic as? [String : AnyObject], context: nil).size

return strSize.height

}

这样就可以根据后台返回的数据进行不同高度的设置了