如果你事先知道要输入的数字数量(例如一个4位数的PIN)，你可以在按4次键后自动退出，就像我对这个类似问题的回答:

取消数字垫

在这种情况下，不需要额外的done按钮。

使用扩展的Swift 3解决方案。如果你在你的应用程序中有几个数值的UITextField对象，这是理想的，因为它可以灵活地决定，对于每个UITextField，当点击完成或取消时是否执行自定义操作。

//
//  UITextField+DoneCancelToolbar.swift
//

import UIKit

extension UITextField {
    func addDoneCancelToolbar(onDone: (target: Any, action: Selector)? = nil, onCancel: (target: Any, action: Selector)? = nil) {     
        let onCancel = onCancel ?? (target: self, action: #selector(cancelButtonTapped))
        let onDone = onDone ?? (target: self, action: #selector(doneButtonTapped))

        let toolbar: UIToolbar = UIToolbar()
        toolbar.barStyle = .default
        toolbar.items = [
            UIBarButtonItem(title: "Cancel", style: .plain, target: onCancel.target, action: onCancel.action),
            UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: self, action: nil),
            UIBarButtonItem(title: "Done", style: .done, target: onDone.target, action: onDone.action)
        ]
        toolbar.sizeToFit()

        self.inputAccessoryView = toolbar
    }

    // Default actions:  
    func doneButtonTapped() { self.resignFirstResponder() }
    func cancelButtonTapped() { self.resignFirstResponder() }
}

使用默认动作的示例:

//
// MyViewController.swift
//

@IBOutlet weak var myNumericTextField: UITextField! {
    didSet { myNumericTextField?.addDoneCancelToolbar() }
}

使用自定义完成动作的示例:

//
// MyViewController.swift
//

@IBOutlet weak var myNumericTextField: UITextField! {
    didSet { 
        myNumericTextField?.addDoneCancelToolbar(onDone: (target: self, action: #selector(doneButtonTappedForMyNumericTextField))) 
    }
}

func doneButtonTappedForMyNumericTextField() { 
    print("Done"); 
    myNumericTextField.resignFirstResponder() 
}

我发现@user1258240的答案是非常简洁的，因为这并不像设置一个returnKeyType属性那么简单。

只是想贡献我自己的“可重用”方法:

func SetDoneToolbar(field:UITextField) {
    let doneToolbar:UIToolbar = UIToolbar()

    doneToolbar.items=[
        UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace, target: self, action: nil),
        UIBarButtonItem(title: "Done", style: UIBarButtonItem.Style.plain, target: self, action: #selector(ViewController.dismissKeyboard))
    ]

    doneToolbar.sizeToFit()
    field.inputAccessoryView = doneToolbar
}

override func viewDidLoad() {
    super.viewDidLoad()

    SetDoneToolbar(field: UITextField_1)
    SetDoneToolbar(field: UITextField_2)
    SetDoneToolbar(field: UITextField_3)
    SetDoneToolbar(field: UITextField_N)
}

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。

我所见过的技巧是创建一个与整个视图大小相同的自定义透明按钮，然后在其click方法中，让文本字段辞去first responder。因此，用户可以单击字段之外的任何地方来取消键盘。

在UIKeyboardTypeNumberPad和缺少返回键的解决方案很好，但只有当屏幕上没有其他非数字pad文本字段时。

我把这段代码变成一个UIViewController你可以简单地子类化它来让数字垫工作。您需要从上面的链接获取图标。

NumberPadViewController.h:

#import <UIKit/UIKit.h>

@interface NumberPadViewController : UIViewController {
    UIImage *numberPadDoneImageNormal;
    UIImage *numberPadDoneImageHighlighted;
    UIButton *numberPadDoneButton;
}

@property (nonatomic, retain) UIImage *numberPadDoneImageNormal;
@property (nonatomic, retain) UIImage *numberPadDoneImageHighlighted;
@property (nonatomic, retain) UIButton *numberPadDoneButton;

- (IBAction)numberPadDoneButton:(id)sender;

@end

和NumberPadViewController.m:

#import "NumberPadViewController.h"

@implementation NumberPadViewController

@synthesize numberPadDoneImageNormal;
@synthesize numberPadDoneImageHighlighted;
@synthesize numberPadDoneButton;

- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle {
    if ([super initWithNibName:nibName bundle:nibBundle] == nil)
        return nil;
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.0) {
        self.numberPadDoneImageNormal = [UIImage imageNamed:@"DoneUp3.png"];
        self.numberPadDoneImageHighlighted = [UIImage imageNamed:@"DoneDown3.png"];
    } else {        
        self.numberPadDoneImageNormal = [UIImage imageNamed:@"DoneUp.png"];
        self.numberPadDoneImageHighlighted = [UIImage imageNamed:@"DoneDown.png"];
    }        
    return self;
}

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

    // Add listener for keyboard display events
    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];
    }

    // Add listener for all text fields starting to be edited
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(textFieldDidBeginEditing:)
                                                 name:UITextFieldTextDidBeginEditingNotification 
                                               object:nil];
}

- (void)viewWillDisappear:(BOOL)animated {
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                        name:UIKeyboardDidShowNotification 
                                                      object:nil];      
    } else {
        [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                        name:UIKeyboardWillShowNotification 
                                                      object:nil];
    }
    [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                    name:UITextFieldTextDidBeginEditingNotification 
                                                  object:nil];
    [super viewWillDisappear:animated];
}

- (UIView *)findFirstResponderUnder:(UIView *)root {
    if (root.isFirstResponder)
        return root;    
    for (UIView *subView in root.subviews) {
        UIView *firstResponder = [self findFirstResponderUnder:subView];        
        if (firstResponder != nil)
            return firstResponder;
    }
    return nil;
}

- (UITextField *)findFirstResponderTextField {
    UIResponder *firstResponder = [self findFirstResponderUnder:[self.view window]];
    if (![firstResponder isKindOfClass:[UITextField class]])
        return nil;
    return (UITextField *)firstResponder;
}

- (void)updateKeyboardButtonFor:(UITextField *)textField {

    // Remove any previous button
    [self.numberPadDoneButton removeFromSuperview];
    self.numberPadDoneButton = nil;

    // Does the text field use a number pad?
    if (textField.keyboardType != UIKeyboardTypeNumberPad)
        return;

    // If there's no keyboard yet, don't do anything
    if ([[[UIApplication sharedApplication] windows] count] < 2)
        return;
    UIWindow *keyboardWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];

    // Create new custom button
    self.numberPadDoneButton = [UIButton buttonWithType:UIButtonTypeCustom];
    self.numberPadDoneButton.frame = CGRectMake(0, 163, 106, 53);
    self.numberPadDoneButton.adjustsImageWhenHighlighted = FALSE;
    [self.numberPadDoneButton setImage:self.numberPadDoneImageNormal forState:UIControlStateNormal];
    [self.numberPadDoneButton setImage:self.numberPadDoneImageHighlighted forState:UIControlStateHighlighted];
    [self.numberPadDoneButton addTarget:self action:@selector(numberPadDoneButton:) forControlEvents:UIControlEventTouchUpInside];

    // Locate keyboard view and add button
    NSString *keyboardPrefix = [[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2 ? @"<UIPeripheralHost" : @"<UIKeyboard";
    for (UIView *subView in keyboardWindow.subviews) {
        if ([[subView description] hasPrefix:keyboardPrefix]) {
            [subView addSubview:self.numberPadDoneButton];
            [self.numberPadDoneButton addTarget:self action:@selector(numberPadDoneButton:) forControlEvents:UIControlEventTouchUpInside];
            break;
        }
    }
}

- (void)textFieldDidBeginEditing:(NSNotification *)note {
    [self updateKeyboardButtonFor:[note object]];
}

- (void)keyboardWillShow:(NSNotification *)note {
    [self updateKeyboardButtonFor:[self findFirstResponderTextField]];
}

- (void)keyboardDidShow:(NSNotification *)note {
    [self updateKeyboardButtonFor:[self findFirstResponderTextField]];
}

- (IBAction)numberPadDoneButton:(id)sender {
    UITextField *textField = [self findFirstResponderTextField];
    [textField resignFirstResponder];
}

- (void)dealloc {
    [numberPadDoneImageNormal release];
    [numberPadDoneImageHighlighted release];
    [numberPadDoneButton release];
    [super dealloc];
}

@end

享受。