MADismissiveTextView處理釋放鍵盤輸入

MADismissiveTextView 是 UITextView 的子類用來處理釋放鍵盤輸入。

示例代碼：

UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 44, 320, 416)];
[self.view addSubview:scrollView];

MADismissiveTextView *textView = [[MADismissiveTextView alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
textView.dismissivePanGestureRecognizer = scrollView.panGestureRecognizer;
textView.keyboardDelegate = self;
[self.view addSubview:textView];