试试这个:

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

    return YES;

}

- (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;
}

使用导航控制器托管一个栏来解除键盘:

在.h文件中:

UIBarButtonItem* dismissKeyboardButton;

在.m文件中:

- (void)viewDidLoad {
    dismissKeyboardButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissKeyboard)];
}

-(void)textViewDidBeginEditing:(UITextView *)textView {
    self.navigationItem.rightBarButtonItem = dismissKeyboardButton;
}

-(void)textFieldDidBeginEditing:(UITextField *)textField {
    self.navigationItem.rightBarButtonItem = dismissKeyboardButton;
}

-(void)dismissKeyboard {
    [self.textField resignFirstResponder];
    [self.textView resignFirstResponder];
    //or replace this with your regular right button
    self.navigationItem.rightBarButtonItem = nil;
}

在使用uitextview时还有另一个解决方案， 你可以添加工具栏作为InputAccessoryView在“textViewShouldBeginEditing”，并从这个工具栏的完成按钮，你可以解雇键盘，这是如下代码:

在viewDidLoad

toolBar = [[UIToolbar alloc]initWithFrame:CGRectMake(0, 0, 320, 44)]; //toolbar is uitoolbar object
toolBar.barStyle = UIBarStyleBlackOpaque;
UIBarButtonItem *btnDone = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(btnClickedDone:)];
[toolBar setItems:[NSArray arrayWithObject:btnDone]];

在textviewdelegate方法

- (BOOL)textViewShouldBeginEditing:(UITextView *)textView
{
     [textView setInputAccessoryView:toolBar];
     return YES;
}

在操作按钮完成，这是在工具栏如下:

-(IBAction)btnClickedDone:(id)sender
{
    [self.view endEditing:YES];
}

就像matt对samvermette的评论一样，我也不喜欢检测“\n”的想法。返回键在UITextView中是有原因的，当然是去下一行。

在我看来，最好的解决方案是模仿iPhone的消息应用程序-这是在键盘上添加工具栏(和按钮)。

我从以下博客文章中得到了代码:

http://www.iosdevnotes.com/2011/02/iphone-keyboard-toolbar/

步骤:

-添加工具栏到你的XIB文件-设置高度为460

-添加工具栏按钮项(如果尚未添加)。如果需要右对齐，还可以将灵活的工具栏按钮项添加到XIB，并移动工具栏按钮项

-创建将按钮项目链接到resignFirstResponder的动作，如下所示:

- (IBAction)hideKeyboard:(id)sender {
    [yourUITextView resignFirstResponder];
}

套:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];

    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}

- (void)keyboardWillShow:(NSNotification *)notification {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3];

    CGRect frame = self.keyboardToolbar.frame;
    frame.origin.y = self.view.frame.size.height - 260.0;
    self.keyboardToolbar.frame = frame;

    [UIView commitAnimations];
}

- (void)keyboardWillHide:(NSNotification *)notification {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3];

    CGRect frame = self.keyboardToolbar.frame;
    frame.origin.y = self.view.frame.size.height;
    self.keyboardToolbar.frame = frame;

    [UIView commitAnimations];
}

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;

    }