杰里米的回答不太适合我，我想是因为我在一个选项卡视图中有一个导航堆栈，上面有一个模态对话框。我现在使用下面的，它是为我工作，但你的里程可能会有所不同。

 // dismiss keyboard (mostly macro)
[[UIApplication sharedApplication].delegate dismissKeyboard]; // call this in your to app dismiss the keybaord

// --- dismiss keyboard (in indexAppDelegate.h) (mostly macro)
- (void)dismissKeyboard;

// --- dismiss keyboard (in indexAppDelegate.m) (mostly macro)
// do this from anywhere to dismiss the keybard
- (void)dismissKeyboard {    // from: http://stackoverflow.com/questions/741185/easy-way-to-dismiss-keyboard

    UITextField *tempTextField = [[UITextField alloc] initWithFrame:CGRectZero];

    UIViewController *myRootViewController = <#viewController#>; // for simple apps (INPUT: viewController is whatever your root controller is called.  Probably is a way to determine this progragrammatically)
    UIViewController *uivc;
    if (myRootViewController.navigationController != nil) { // for when there is a nav stack
        uivc = myRootViewController.navigationController;
    } else {
        uivc = myRootViewController;
    }

    if (uivc.modalViewController != nil) { // for when there is something modal
        uivc = uivc.modalViewController;
    } 

    [uivc.view  addSubview:tempTextField];

    [tempTextField becomeFirstResponder];
    [tempTextField resignFirstResponder];
    [tempTextField removeFromSuperview];
    [tempTextField release];

}

我最近需要使用的一个稍微健壮一点的方法:

- (void) dismissKeyboard {
    NSArray *windows = [UIApplication sharedApplication].windows;

    for(UIWindow *window in windows) [window endEditing:true];

    //  Or if you're only working with one UIWindow:

    [[UIApplication sharedApplication].keyWindow endEditing:true];
}

我发现其他一些“全局”方法不起作用(例如，UIWebView和WKWebView拒绝辞职)。

在swift 3中，您可以执行以下操作

UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)

把这个藏在实用课里吧。

+ (void)dismissKeyboard {
    [self globalResignFirstResponder];
}

+ (void) globalResignFirstResponder {
    UIWindow * window = [[UIApplication sharedApplication] keyWindow];
    for (UIView * view in [window subviews]){
        [self globalResignFirstResponderRec:view];
    }
}

+ (void) globalResignFirstResponderRec:(UIView*) view {
    if ([view respondsToSelector:@selector(resignFirstResponder)]){
        [view resignFirstResponder];
    }
    for (UIView * subview in [view subviews]){
        [self globalResignFirstResponderRec:subview];
    }
}

你必须使用其中一种方法，

[self.view endEditing:YES];

or

[self.textField resignFirstResponder];

我讨厌没有“全局”的方法在不使用私有API调用的情况下以编程方式取消键盘。我经常需要在不知道哪个对象是第一个响应器的情况下以编程方式关闭键盘。我使用Objective-C运行时API检查self，枚举它的所有属性，取出那些类型为UITextField的属性，并将resignFirstResponder消息发送给它们。

做这件事不应该这么难…