C singleton look like?

My singleton accessor method is usually some variant of:

static MyClass *gInstance = NULL;

+ (MyClass *)instance
{
    @synchronized(self)
    {
        if (gInstance == NULL)
            gInstance = [[self alloc] init];
    }

    return(gInstance);
}

What could I be doing to improve this?

---

Another option is to use the +(void)initialize method. From the documentation:

The runtime sends initialize to each class in a program exactly one time just before the class, or any class that inherits from it, is sent its first message from within the program. (Thus the method may never be invoked if the class is not used.) The runtime sends the initialize message to classes in a thread-safe manner. Superclasses receive this message before their subclasses.

So you could do something akin to this:

static MySingleton *sharedSingleton;

+ (void)initialize
{
    static BOOL initialized = NO;
    if(!initialized)
    {
        initialized = YES;
        sharedSingleton = [[MySingleton alloc] init];
    }
}

---

@interface MySingleton : NSObject
{
}

+ (MySingleton *)sharedSingleton;
@end

@implementation MySingleton

+ (MySingleton *)sharedSingleton
{
  static MySingleton *sharedSingleton;

  @synchronized(self)
  {
    if (!sharedSingleton)
      sharedSingleton = [[MySingleton alloc] init];

    return sharedSingleton;
  }
}

@end

[资源]

---

根据我下面的其他答案，我认为你应该这样做：

+ (id)sharedFoo
{
    static dispatch_once_t once;
    static MyFoo *sharedFoo;
    dispatch_once(&once, ^ { sharedFoo = [[self alloc] init]; });
    return sharedFoo;
}

链接地址: http://www.djcxy.com/p/20688.html

上一篇: 视图控制器之间进行通信的最佳方式是什么？

下一篇: C单例看起来像？