iOS UITextView dismiss keyboard

使用者在 UITextView 輸入完畢後，無法將鍵盤關閉，
以下方法，是透過 keyboard 的 return key 去關閉鍵盤

Quick Start

繼承UITextViewDelegate

@interface TestViewController () <UITextViewDelegate>

設定UITextView delegate

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.    
    self.txTextView.delegate = self;
}

實作 UITextView shouldChangeTextInRange

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    
    if ([text isEqualToString:@"\n"]) {
        [textView resignFirstResponder];
        return NO;
    }
    return YES;
}