如何在Objective-C中处理我自己的sharedInstance？

@interface MySingleton : NSObject

+ (instancetype)sharedInstance;

@end

#import "MySingleton.h"

@implementation MySingleton

+ (instancetype)sharedInstance {
    static MySingleton *_sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedInstance = [[MySingleton alloc] init];
    });
    return _sharedInstance;
}

@end

MySingleton *singleton = [MySingleton sharedInstance];