objective-c - 如何使输出依赖于 UIPicker 行选择

Question

我需要一个组件 UIPicker 来显示不同的文本并根据选择的行执行不同的操作。我正在定义文本，所以它不是选择器读取的内容。第一个、第二个和第三个都是 NSString。我无法找出正确的代码来使操作依赖于 UIPicker 行。这是我最后一次尝试...

-(IBAction)example {
        if (UIPickerView *)examplepick didSelectRow:(NSInteger)0 inComponent:(NSInteger)0  {
        NSString *finalMessage = [[NSString alloc] initWithFormat: @"Say \"%@\"", first];
        select1.text = first;
        display.text = finalMessage;
    } else {
        if (UIPickerView *)examplepick didSelectRow:(NSInteger)1 inComponent:(NSInteger)0 {
            NSString *finalMessage = [[NSString alloc] initWithFormat: @"Say \"%@\"", second;
            select1.text = second;
            display.text = finalMessage;
        } else {
            if (UIPickerView *)examplepick didSelectRow:(NSInteger)2 inComponent:(NSInteger)0 {
                NSString *finalMessage = [[NSString alloc] initWithFormat: @"Say \"%@\"", third];
                select1.text = third;
                display.text = finalMessage;
           }
       }
    }
}

Answer 1

didSelectRow:inComponent:是在用户操作上调用的委托方法。你不应该在这里调用它。您需要的selectedRowInComponent:是UIPickerView. 这是使用它的示例的粗略实现。

-(IBAction)example {
    switch([example selectedRowInComponent:0]) {
    case 0:
        select1.text = first;
        display.text = [NSString stringWithFormat:@"Say \"%@\"", first];
        break;

    case 1:
        select1.text = second;
        display.text = [NSString stringWithFormat:@"Say \"%@\"", second];
        break;

    case 2:
        select1.text = third;
        display.text = [NSString stringWithFormat:@"Say \"%@\"", second];
        break;

    default:
        break;
    }
}