我发现josebama的回答是这个帖子中最完整、最干净的答案。

下面是Swift 4的语法:

func textView(_ textView: UITextView, shouldChangeTextIn _: NSRange, replacementText text: String) -> Bool {
    let resultRange = text.rangeOfCharacter(from: CharacterSet.newlines, options: .backwards)
    if text.count == 1 && resultRange != nil {
        textView.resignFirstResponder()
        // Do any additional stuff here
        return false
    }
    return true
}

+ (void)addDoneButtonToControl:(id)txtFieldOrTextView
{
    if([txtFieldOrTextView isKindOfClass:[UITextField class]])
    {
        txtFieldOrTextView = (UITextField *)txtFieldOrTextView;
    }
    else if([txtFieldOrTextView isKindOfClass:[UITextView class]])
    {
        txtFieldOrTextView = (UITextView *)txtFieldOrTextView;
    }

    UIToolbar* numberToolbar = [[UIToolbar alloc]initWithFrame:CGRectMake(0,
                                                                          0,
                                                                          [Global returnDeviceWidth],
                                                                          50)];
    numberToolbar.barStyle = UIBarStyleDefault;


    UIBarButtonItem *btnDone = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"btn_return"]
                                                                style:UIBarButtonItemStyleBordered
                                                               target:txtFieldOrTextView
                                                               action:@selector(resignFirstResponder)];

    numberToolbar.items = [NSArray arrayWithObjects:btnDone,nil];
    [numberToolbar sizeToFit];

    if([txtFieldOrTextView isKindOfClass:[UITextField class]])
    {
         ((UITextField *)txtFieldOrTextView).inputAccessoryView = numberToolbar;
    }
    else if([txtFieldOrTextView isKindOfClass:[UITextView class]])
    {
         ((UITextView *)txtFieldOrTextView).inputAccessoryView = numberToolbar;
    }
}

试试这个。

NSInteger lengthOfText = [[textView.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] length];

//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;
}

银行的国际代码

在你的类/视图中实现UITextViewDelegate，如下所示:

class MyClass: UITextViewDelegate  { ...

设置textView委托为self

myTextView.delegate = self

然后实现以下内容:

  func textViewDidChange(_ textView: UITextView) {
    if textView.text.characters.count >= 1 {

        if let lastChar = textView.text.characters.last {

            if(lastChar == "\n"){

              textView.text = textView.text.substring(to: textView.text.index(before: textView.text.endIndex))
              textView.resignFirstResponder()
            }
        }
    }
}

编辑 我更新了代码，因为它从来都不是一个好主意，改变用户在文本框的输入，以解决问题，而不是在黑客代码完成后重新设置状态。

用另一种方法解决了这个问题。

Create a button that will be placed in the background From the Attribute Inspector, change the button type to custom, and the makes the button transparent. Expand the button to cover the whole view, and make sure the button is behind all the other object. Easy way to do this is to drag the button to the top of list view in the View Control drag the button to the viewController.h file and create an action (Sent Event: Touch Up Inside) like : (IBAction)ExitKeyboard:(id)sender; In ViewController.m should look like : (IBAction)ExitKeyboard:(id)sender { [self.view endEditing:TRUE]; } Run app, and when you click away from the TextView, the keyboard disappears