ios - 访问在 alertController 中声明的变量

Question

我正在尝试创建一个提醒，提示用户为他们导入到乐谱显示应用程序中的歌曲命名。

我已经为这个命名过程创建了一个函数:

- (NSString *)nameImportedSong {
    NSString *songName;

    UIAlertController * alertController = [UIAlertController alertControllerWithTitle: @"New Song"
                                                                              message: @"Choose a song name"
                                                                       preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
        textField.placeholder = @"song name";
        textField.textColor = [UIColor blueColor];
        textField.clearButtonMode = UITextFieldViewModeWhileEditing;
        textField.borderStyle = UITextBorderStyleRoundedRect;
    }];
    [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        NSArray * textfields = alertController.textFields;
        UITextField * namefield = textfields[0];
        NSString *chosenSongName = [NSString stringWithFormat:@"%@", namefield.text];

    }]];

    songName = ; // <-------------how do I assign chosenSongName to songName?

    [self presentViewController:alertController animated:YES completion:nil];

    return songName;

}

如何在警报之外将警报中的 chosenSongName 分配给我的 songName 变量？

Answer 1

为变量使用__block关键字

__block NSString *chosenSongName;

 [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
    NSArray * textfields = alertController.textFields;
    UITextField * namefield = textfields[0];
    chosenSongName = [NSString stringWithFormat:@"%@", namefield.text];

}]];

songName = chosenSongName;
NSLog(@"chosenSongName = %@",chosenSongName);