查看NSObject类initialize方法方法的文档时，发现其可以用来实现单例模块。

代码如下：

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@implementation QBaseObject

static QBaseObject *_sharedBaseObject;
static BOOL _initialized = NO;

+ (void)initialize
{
    if (!_initialized)
    {
        _sharedBaseObject = [[QBaseObject alloc] init];
        _initialized = YES;
    }
}

@end