- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range  replacementText:(NSString *)text
{
    if (range.length==0) {
        if ([text isEqualToString:@"\n"]) {
            [txtView resignFirstResponder];
            if(textView.returnKeyType== UIReturnKeyGo){

                [self PreviewLatter];
                return NO;
            }
            return NO;
        }
    }   return YES;
}

//你可以使用这个…

步骤1。第一步是确保声明了对UITextViewDelegate协议的支持。这是在你的头文件中完成的，例如这里的头文件叫做

EditorController。h:

@interface EditorController : UIViewController  {
  UITextView *messageTextView;
}

@property (nonatomic, retain) UITextView *messageTextView;

@end

步骤2。接下来你需要将控制器注册为UITextView的委托。从上面的例子继续，这里是我如何用EditorController作为委托初始化UITextView…

- (id) init {
    if (self = [super init]) {
        // define the area and location for the UITextView
        CGRect tfFrame = CGRectMake(10, 10, 300, 100);
        messageTextView = [[UITextView alloc] initWithFrame:tfFrame];
        // make sure that it is editable
        messageTextView.editable = YES;

        // add the controller as the delegate
        messageTextView.delegate = self;
    }

步骤3。现在拼图的最后一块是采取行动响应shouldCahngeTextInRange消息如下:

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range 
  replacementText:(NSString *)text
{
    // Any new character added is passed in as the "text" parameter
    if ([text isEqualToString:@"\n"]) {
        // Be sure to test for equality using the "isEqualToString" message
        [textView resignFirstResponder];

        // Return FALSE so that the final '\n' character doesn't get added
        return FALSE;
    }
    // For any other character return TRUE so that the text gets added to the view
    return TRUE;
}

问题问的是如何用返回键来做，但我认为这可以帮助那些想要在使用UITextView时让键盘消失的人:

private func addToolBarForTextView() {
    let textViewToolbar: UIToolbar = UIToolbar()
    textViewToolbar.barStyle = .default
    textViewToolbar.items = [
        UIBarButtonItem(title: "Cancel", style: .done,
                  target: self, action: #selector(cancelInput)),
        UIBarButtonItem(barButtonSystemItem: .flexibleSpace,
                  target: self, action: nil),
        UIBarButtonItem(title: "Post Reply", style: .done,
                  target: self, action: #selector(doneInput))
    ]
    textViewToolbar.sizeToFit()
    yourTextView.inputAccessoryView = textViewToolbar
}

@objc func cancelInput() { print("cancel") }
@objc func doneInput() { print("done") }

override func viewDidLoad() {
    super.viewDidLoad()
    addToolBarForTextView()
}

在viewDidLoad或其他生命周期方法中调用addToolBarForTextView()。

这对我来说似乎是一个完美的解决方案。

欢呼,

穆拉特

在viewDidLoad中添加一个观察者

[[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(textViewKeyPressed:) name: UITextViewTextDidChangeNotification object: nil];

然后使用选择器检查"\n"

-(void) textViewKeyPressed: (NSNotification*) notification {

  if ([[[notification object] text] hasSuffix:@"\n"])
  {
    [[notification object] resignFirstResponder];
  }
}

它确实使用“\n”，而不是专门检查返回键，但我认为这是可以的。

更新

参见下面ribto的答案，它使用[NSCharacterSet newlineCharacterSet]来代替\n

我知道这已经回答了，但我真的不喜欢使用字符串字面量的换行，所以这是我所做的。

- (BOOL)textView:(UITextView *)txtView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    if( [text rangeOfCharacterFromSet:[NSCharacterSet newlineCharacterSet]].location == NSNotFound ) {
        return YES;
    }

    [txtView resignFirstResponder];
    return NO;
}

Swift 4.0更新:

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if (text as NSString).rangeOfCharacter(from: CharacterSet.newlines).location == NSNotFound {
    return true
}
txtView.resignFirstResponder()
return false
}

我想我应该把这个片段放在这里:

确保声明了对UITextViewDelegate协议的支持。

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

    if([text isEqualToString:@"\n"]) {
        [textView resignFirstResponder];
        return NO;
    }

    return YES;
}

Swift 4.0更新:

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    if text == "\n" {
        textView.resignFirstResponder()
        return false
    }
    return true
}