OC 创建单例

new_gist_file

//
//  UserConext.m
//  HelloWorld
//
//  Created by Terry on 2013-10-07.
//  Copyright (c) 2013 Terry. All rights reserved.
//

#import "UserConext.h"

@implementation UserConext

static UserConext *singleton = nil;

+(id)sharedUserContext {
    @synchronized(self){
        if (!singleton) {
            singleton = [[UserConext alloc] init];
        }
    }
    return self;
}

@end