如何让UIViewController自动弹出PickerView

因为响应者的一下属性inputView和inputAccessoryView都是只读的，所以如果想要指定弹出的view就要override 下面两个属性的get和set方法

UIResponder (UIResponderInputViewAdditions)

@property (readonly,retain) UIView *inputView NS_AVAILABLE_IOS(3_2);            

@property (readonly,retain) UIView *inputAccessoryView NS_AVAILABLE_IOS(3_2); 

//write this code in UIViewController//UIViewController default is NO.//override- (BOOL)canBecomeFirstResponder {    return YES;}//override- (UIView*) inputView {    return [[UIDatePicker alloc] init];}