[NSCFNumber isEqualToString:]:发送到实例的无法识别的选择器

Question

好吧,我有以下常见问题

[NSCFNumber isEqualToString:]: unrecognized selector sent to instance

但这次我不确定如何解决它.

这是宣言中的 viewDidLoad:

- (void)viewDidLoad {

    [super viewDidLoad];

    NSMutableArray *tempHours = [NSMutableArray array];
    for (int i = 0; i < 12; i++) { 
        [tempHours addObject:[NSNumber numberWithInt:(i+1)]];
    }
    self.hours = tempHours; // 'hours' is a synthesized NSArray property of the ViewController
    [tempHours release];

  // two more similar array declarations here

}

这是UIPickerView的代码方法,其中东西中断(例如,if语句)

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {

    NSString *stringIndex = [NSString stringWithFormat:@"Row #%d", row];

    if(component == 0) {
        return stringIndex = [self.hours objectAtIndex:row];
    }

    // more code for other components (of the same form) here

    return stringIndex;
}

我想我需要NSArray的NSNumber对象被类型化为字符串.如何使用该声明正确执行此操作:

stringIndex = [self.hours objectAtIndex:row];

谢谢!

Answer 1

return [NSString stringWithFormat:@"%@",[self.hours objectAtIndex:row]];

Answer 2

你正在返回一个NSNumber所持有的东西self.hours.由于NSString是预期的返回值,你应该通过创建一个字符串:

[NSString stringWithFormat:@"%@", [self.hours objectAtIndex:row]];

或重新评估你的意图.你真的想以这种方式存储索引,还是想存储NSStrings？