Question

If I have a Class (MyClass) with an attribute myAttribute, I can t use it in a subclass (MySubclass) without calling self.myAttribute. I have not problem with this sort of code when running the app with the simulator. You might be wondering: "why does she do this?". It s quite easy to add "self" everywhere. The problem is that in MySubclass I m overriding some accessor methods of MyClass. Here s an example:

- (NSDateFormatter *)dateFormatter
{
    if (dateFormatter == nil)
    {
        dateFormatter = [[NSDateFormatter alloc] init];
        // Do other stuff with the dateFormatter
    }

    return dateFormatter;
}

我可以说自己。日期炉内的形式,因为它会造成无休止的 lo。我可以支持我处理该问题的班子,但处理此类问题可能是一个良好和简单的解决办法。

感谢!

Answer 1

你们必须记住这一点。财产与[不动产]完全相同。

财产名称和案例变数不得有相同的名称以避免任何混淆。

Best way is to always preprend a common prefix to ivars.

@interface MyClass {
  // You don t have to declare iVar. Feel free to remove line.
  NSDateFormatter * iVarDateFormatter;
}

@property (retain) NSDateFormatter * dateFormatter;

@end

执行

@implementation MyClass
@synthetize dateFormatter= iVarDateFormatter;
...
@end

因此,你可以写:

- (NSDateFormatter *) dateFormatter
{
    if ( nil == iVarDateFormatter )
    {
        iVarDateFormatter = [[NSDateFormatter alloc] init];
        // Do other stuff with the dateFormatter
    }

    return iVarDateFormatter;
}

就单吨物体而言,甚至更好,使用GCD- 信号!

- (NSDateFormatter *) dateFormatter
{
    static dispatch_once_t pred;

    dispatch_once(& pred, ^{
        iVarDateFormatter = [[NSDateFormatter alloc] init];
        // Do other stuff with the dateFormatter
    });

    return iVarDateFormatter;
}

友情链接