GCD 多线程 ---的记录 iOS

先写一个GCD 

static  UserInfoVoModel *userInfoShare = nil;
+(instancetype)shareUserInfoVoModel
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        userInfoShare = [[UserInfoVoModel alloc] init];
       
    });
    return userInfoShare;
    
}