仅在输入后启用UIAlertAction的UIAlertAction [英] Enable UIAlertAction of UIAlertController only after input

问题描述

我使用 UIAlertController 来显示一个带有 UITextField 的对话框和一个 UIAlertAction 标有Ok的按钮。如何在 UITextField 中输入多个字符（例如5个字符）之前禁用该按钮？

I am using a UIAlertController to present a dialog with a UITextField and one UIAlertAction button labeled "Ok". How do I disable the button until a number of characters (say 5 characters) are input into the UITextField?

推荐答案

在头文件中添加以下属性

Add following property in your header file

@property(nonatomic, strong)UIAlertAction *okAction;   

然后在 viewDidLoad 中复制以下代码你的 ViewController的方法

then copy the following code in your viewDidLoad method of your ViewController

self.okAction = [UIAlertAction actionWithTitle:@"OK"
                                         style:UIAlertActionStyleDefault
                                       handler:nil];
self.okAction.enabled = NO;

UIAlertController *controller = [UIAlertController alertControllerWithTitle:nil
                                                                    message:@"Enter your text"
                                                             preferredStyle:UIAlertControllerStyleAlert];

[controller addTextFieldWithConfigurationHandler:^(UITextField *textField) {

    textField.delegate = self;
}];

[controller addAction:self.okAction];
[self presentViewController:controller animated:YES completion:nil];

同时实现以下 UITextField 委托方法你的类

Also implement the following UITextField delegate method in your Class

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    NSString *finalString = [textField.text stringByReplacingCharactersInRange:range withString:string];
   [self.okAction setEnabled:(finalString.length >= 5)];
   return YES;
}

这应该有效

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