let dic = NSMutableDictionary()
dic.setValue("", forKey:"")
-[__NSCFDictionary setObject:forKey:]: mutating method sent to immutable object'
明明定义了NSMutableDictionary,但是使用setValue是依旧报错
解决方法-》
let dic = ["":"","":""] as [NSObject:AnyObject]
let newDic = NSMutableDictionary(dictionary: dic, copyItems:true)
newDic.setValue("", forKey:"")