我目前正在将一个fork的框架升级到Swift3。publicconvenienceinit(object:Object,keyPath:String,options:NSKeyValueObservingOptions=[],block:@escaping(_object:Object,_change:Change,_kvo:KVObserver)->Void){self.init(__object:object,keyPath:keyPath,options:options,block:{(object,change,kvo)inblock(unsafeDowncast(objec