Alert 警告框

创建Alert 警告框只需要创建UIAlertController 对象显示出来即可

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    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"title" message:@"message" preferredStyle:UIAlertControllerStyleAlert]; 

    //Action Sheet Style  底部提示框

//        UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Title" message:@"message" preferredStyle:UIAlertControllerStyleActionSheet];

    //添加按钮

    UIAlertAction *actionCancel = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnullaction) {

        //点击后执行

        NSLog(@"点击了取消按钮");

    }];

    //将AlertAction添加到AlertController

    [alert addAction:actionCancel]; 

    [self presentViewController:alert animated:YES completion:^{

        //弹出警告框

      NSLog(@"presentViewController弹出警告框所执行的内容");

    }];

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为AlertController添加文本输入框

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     [alert addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {

        //添加输入框

        //设置TextField提示信息

        textField.placeholder = @"输入框";

    }];  

     [alert addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {

        //添加输入框

        //设置TextField提示信息

        textField.placeholder = @"第二个输入框";

    }];

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//创建UIAlertView控件    UIAlertView 在9.0后弃用

//    UIAlertView *alert = [[UIAlertView alloc]

//                          initWithTitle:@"指定标题"

//                          message:@"指定消息" delegate:self //指定委托对象

//                        cancelButtonTitle:@"确定" //为底部取消按钮设置标题

//                        otherButtonTitles:@"按钮一", @"按钮二", nil];

//    [alert show]; //显示alert