试试这个。

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

你也可以隐藏键盘时，触摸在视图屏幕:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
     UITouch * touch = [touches anyObject];
     if(touch.phase == UITouchPhaseBegan) {
        [txtDetail resignFirstResponder];
      }
 }

- (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;
}

我使用这段代码来更改响应器。

 - (BOOL)textView:(UITextView*) textView shouldChangeTextInRange: (NSRange) range replacementText: (NSString*) text
    {
        if ([text isEqualToString:@"\n"]) {
            //[textView resignFirstResponder];
            //return YES;
            NSInteger nextTag = textView.tag + 1;
            // Try to find next responder
            UIResponder* nextResponder = [self.view viewWithTag:nextTag];
            if (nextResponder) {
                // Found next responder, so set it.
                [nextResponder becomeFirstResponder];
            } else {
                // Not found, so remove keyboard.
                [textView resignFirstResponder];
            }
            return NO; 


            return NO;
        }
        return YES;

    }

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
}

试试这个:

 - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
    if ([text isEqualToString:@"\n"]) {
        [self.view endEditing:YES];
    }

    return YES;

}