UITextField用NSUndoManager支持替换文本

Question

我只是使用一个简单的

self.customerTextField.text = @"text";

但我希望有撤销支持，如果他们摇动手机，他们可以撤销更改。

我有点不知道如何完成这件事。我找到的所有示例都是针对UITextView的。

======================== 当前迭代的代码 ======================

-(void)getUniqueItemID {
    [self.inventoryLibrarian generateUniqueItemIDwithCompletionBlock:^(NSString *string) {
        [self undoTextFieldEdit:string];
        //self.customTextField.text = string;
    }];
}
- (void)undoTextFieldEdit: (NSString*)string
{
    [self.undoManager registerUndoWithTarget:self
                                    selector:@selector(undoTextFieldEdit:)
                                      object:self.customTextField.text];
    self.customTextField.text = string;
}
-(BOOL)canBecomeFirstResponder {
    return YES;
}

Answer 1

Shake-to-undo
把这一行放到appDelegate的application:didFinishLaunchingWithOptions:方法中:

    application.applicationSupportsShakeToEdit = YES;

和相关的viewController.m

    -(BOOL)canBecomeFirstResponder {
        return YES;
    }

其余代码在viewController.m

中<<p> 属性/strong>
把它放到类扩展中…

    @interface myViewController()
    @property (weak, nonatomic) IBOutlet UITextField *inputTextField;
    @end

将其链接到Interface Builder中的文本字段。

<<p> 撤消方法/strong>
将自身调用添加到重做堆栈

    - (void)undoTextFieldEdit: (NSString*)string
    {
        [self.undoManager registerUndoWithTarget:self
                                        selector:@selector(undoTextFieldEdit:)
                                          object:self.inputTextField.text];
        self.inputTextField.text = string;
    }

(我们不需要创建NSUndoManager实例，我们从UIResponder超类继承一个)

<<p> 撤消操作/strong>
不需要震动撤销，但可能有用…

    - (IBAction)undo:(id)sender {
        [self.undoManager undo];
    }
    - (IBAction)redo:(id)sender {
        [self.undoManager redo];
    }

撤销方法的调用
下面是更改textField内容的两个不同示例…

示例1

设置按钮动作的textField的内容

    - (IBAction)addLabelText:(UIButton*)sender {
        [self.undoManager registerUndoWithTarget:self
                                        selector:@selector(undoTextFieldEdit:)
                                          object:self.inputTextField.text];
        self.inputTextField.text = @"text";
    }

我们可以将其缩短为:

    - (IBAction)addLabelText:(UIButton*)sender {
        [self undoTextFieldEdit: @"text"];
    }

作为undoManager调用在两个方法中是相同的

示例2

直接键盘输入编辑

    #pragma mark - textField delegate methods
    - (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
    {
        [self.undoManager registerUndoWithTarget:self
                                        selector:@selector(undoTextFieldEdit:)
                                          object:textField.text];
        return YES;
    }
    - (BOOL)textFieldShouldReturn:(UITextField *)textField
    {
        //to dismiss the keyboard
        [textField resignFirstResponder];
        return YES;
    }

Answer 2

你不需要做任何事情，它只是工作，除非你禁用它。