ios单例

方式一、单例

+ (SocketUtils *)getInstance;

static SocketUtils *instance = nil;

+ (SocketUtils *)getInstance {
    if (nil == instance) {
        //Socket
        instance = [[SocketUtils alloc] initWithURLRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:WEBSOCKET_SERVER]]];
    }
    return instance;
}

方式二、单例

用dispatch_once函数：

+ (SVProgressHUD*)sharedView {
    static dispatch_once_t once;
    static SVProgressHUD *sharedView;
    dispatch_once(&once, ^ {

        sharedView = [[SVProgressHUD alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    });
    return sharedView;
}