如果我们告诉视图控制器的视图结束编辑，我们也可以让“user touched somewhere else”解决方案更简单:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
 { 
      [super touchesBegan:touches withEvent:event];

      [self.view endEditing:YES]; //YES ignores any textfield refusal to resign
 }

．.． 假设“触摸其他地方会取消键盘”是视图中任何其他可编辑字段所期望的行为。

所有这些关于找到键盘视图并在第三行添加done按钮的实现(这就是为什么按钮。y = 163 b/c键盘的高度是216)是脆弱的，因为iOS不断改变视图层次结构。例如，上述代码都不适用于iOS9。

我认为更安全的方法是找到最顶层的视图，通过[[UIApplication sharedApplication] windows] lastObject]，并在它的左下角添加按钮，doneButton.frame = CGRectMake(0, screen_height - 53,106,53);//人像模式

我在这里描述了iOS 4.2+的一个解决方案，但键盘出现后，解散按钮会消失。这并不可怕，但也不理想。

上面链接的问题中描述的解决方案包括一种更优雅的消除按钮的错觉，我将按钮淡出并垂直移动，以提供键盘和按钮一起消除的外观。

这是最新的代码。只包括 在你的viewController中导入"UIViewController+NumPadReturn.h"

这里是。h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface UIViewController (NumPadReturn)



@end

还有。m

#import "UIViewController+NumPadReturn.h"


@implementation UIViewController (NumPadReturn)

-(void) viewDidLoad{
    // add observer for the respective notifications (depending on the os version)
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        [[NSNotificationCenter defaultCenter] addObserver:self 
                                                 selector:@selector(keyboardDidShow:) 
                                                     name:UIKeyboardDidShowNotification 
                                                   object:nil];     
    } else {
        [[NSNotificationCenter defaultCenter] addObserver:self 
                                                 selector:@selector(keyboardWillShow:) 
                                                     name:UIKeyboardWillShowNotification 
                                                   object:nil];
    }

}


- (void)keyboardWillShow:(NSNotification *)note {
    // if clause is just an additional precaution, you could also dismiss it
    if ([[[UIDevice currentDevice] systemVersion] floatValue] < 3.2) {
        [self addButtonToKeyboard];
    }
}

- (void)keyboardDidShow:(NSNotification *)note {
    // if clause is just an additional precaution, you could also dismiss it
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        [self addButtonToKeyboard];
    }
}

- (void)addButtonToKeyboard {
    // create custom button
    UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
    doneButton.frame = CGRectMake(0, 163, 106, 53);
    doneButton.adjustsImageWhenHighlighted = NO;
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.0) {
        [doneButton setImage:[UIImage imageNamed:@"DoneUp3.png"] forState:UIControlStateNormal];
        [doneButton setImage:[UIImage imageNamed:@"DoneDown3.png"] forState:UIControlStateHighlighted];
    } else {        
        [doneButton setImage:[UIImage imageNamed:@"DoneUp.png"] forState:UIControlStateNormal];
        [doneButton setImage:[UIImage imageNamed:@"DoneDown.png"] forState:UIControlStateHighlighted];
    }
    [doneButton addTarget:self action:@selector(doneButton:) forControlEvents:UIControlEventTouchUpInside];
    // locate keyboard view
    UIWindow* tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];
    UIView* keyboard;
    for(int i=0; i<[tempWindow.subviews count]; i++) {
        keyboard = [tempWindow.subviews objectAtIndex:i];
        // keyboard found, add the button
        if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
            if([[keyboard description] hasPrefix:@"<UIPeripheralHost"] == YES)
                [keyboard addSubview:doneButton];
        } else {
            if([[keyboard description] hasPrefix:@"<UIKeyboard"] == YES)
                [keyboard addSubview:doneButton];
        }
    }
}

- (void)doneButton:(id)sender {
    NSLog(@"doneButton");
    [self.view endEditing:TRUE];
}



@end

对于Swift 2.2，我使用这个

func addDoneButtonOnKeyboard() {
    let doneToolbar: UIToolbar = UIToolbar(frame: CGRectMake(0, 0, self.view.bounds.size.width, 50))

    let flexSpace = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: nil, action: nil)
    let done: UIBarButtonItem = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.Done, target: self, action: #selector(DetailViewController.finishDecimalKeypad))

    var items: [UIBarButtonItem]? = [UIBarButtonItem]()
    items?.append(flexSpace)
    items?.append(done)

    doneToolbar.items = items
    doneToolbar.sizeToFit()
    self.productPrice.inputAccessoryView=doneToolbar
}

func finishDecimalKeypad() {
    self.productPrice?.resignFirstResponder()
}

以下是对Luda的回答的全面检查，并进行了以下更改:

附件视图会自动调整到应用程序框架的宽度 避免使用已弃用的常量UIBarButtonItemStyleBordered Done按钮被实例化为UIBarButtonSystemItemDone

目前“Done”按钮位于附件视图的中央。您可以通过删除相关一侧的空格将其定位在左侧或右侧。

我省略了“取消”按钮，因为默认键盘也没有这个按钮。如果你确实想要一个“取消”按钮，我建议你实例化它为一个UIBarButtonSystemItemCancel，并确保你没有丢弃文本字段中的原始值。在Luda的回答中实现的“取消”行为会用空字符串覆盖值，这可能不是你想要的。

- (void)viewDidLoad {
  [super viewDidLoad];
  float appWidth = CGRectGetWidth([UIScreen mainScreen].applicationFrame);
  UIToolbar *accessoryView = [[UIToolbar alloc]
                              initWithFrame:CGRectMake(0, 0, appWidth, 0.1 * appWidth)];
  UIBarButtonItem *space = [[UIBarButtonItem alloc]
                            initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                            target:nil
                            action:nil];
  UIBarButtonItem *done = [[UIBarButtonItem alloc]
                           initWithBarButtonSystemItem:UIBarButtonSystemItemDone
                           target:self
                           action:@selector(selectDoneButton)];
  accessoryView.items = @[space, done, space];
  self.valueField.inputAccessoryView = accessoryView;
}

- (void)selectDoneButton {
  [self.valueField resignFirstResponder];
}

有关构建附件视图的更多信息，请参阅Apple关于数据输入自定义视图的文档。你可能会想要参考UIToolbar和UIBarButtonItem的参考页面。