客观c中的单身人士

问题描述

限时删除！！

我看到了一个关于客观C书的单例例子。然而，我不知道目标c和其他lang之间的'单身'定义的含义是否存在差异。可以使用[[SingletonClass alloc] init]来创建新对象吗？如果是，如何保证内存中只有一个对象？

I saw a singleton example on objective-c book. However, I don't know if there is difference of meaning of 'singleton' definition between objective-c and other langs. Can this [[SingletonClass alloc] init] still be used to create a new object? If yes, how to guarantee there is only one object in the memory?

#import "SingletonClass.h"

@implementation SingletonClass

static SingletonClass *sharedInstance = nil;

// Get the shared instance and create it if necessary.
+ (SingletonClass*)sharedInstance {
    if (sharedInstance == nil) {
        sharedInstance = [[super allocWithZone:NULL] init];
    }

    return sharedInstance;
}

// We can still have a regular init method, that will get called the first time the             Singleton is used.
- (id)init
{
    self = [super init];

    if (self) {
        // Work your initialising magic here as you normally would
    }

    return self;
}

推荐答案

Colin Wheeler 。

Colin Wheeler has a post on Singletons in Cocoa.

我同意Colin关于Singleton的不合需要。

I agree with Colin about the undesirability of Singletons.

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