摘要： OverviewNSURLRequestobjects represent a URL load request in a manner independent of protocol and URL scheme.NSURLRequest encapsulates two basic data e... 阅读全文

摘要： viewWillAppear:Called when the view is about to made visible. Default does nothing视图即将可见时调用。默认情况下不执行任何操作viewDidAppear:Called when the view has been fu... 阅读全文