iOS中利用inputView 弹出 picker

@property (readwrite) UIView *inputView;
@property (readwrite) UIView *inputAccessoryView;
- (BOOL)isUserInteractionEnabled
{
  return YES;
}
- (BOOL)canBecomeFirstResponder
{
  return YES;
}

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(touchAction)];
  [tap setNumberOfTouchesRequired:1];
  [tap setNumberOfTapsRequired:1];
  [self addGestureRecognizer:tap];