Create singleton using GCD's dispatch_once in Objective-C

Question

If you can target iOS 4.0 or above

Using GCD, is it the best way to create singleton in Objective-C (thread safe)?

+ (instancetype)sharedInstance
{
          


        

Answer 1

instancetype

instancetype is just one of the many language extensions to Objective-C, with more being added with each new release.

Know it, love it.

And take it as an example of how paying attention to the low-level details can give you insights into powerful new ways to transform Objective-C.

Refer here: instancetype

---

+ (instancetype)sharedInstance
{
    static dispatch_once_t once;
    static id sharedInstance;

    dispatch_once(&once, ^
    {
        sharedInstance = [self new];
    });    
    return sharedInstance;
}

---

+ (Class*)sharedInstance
{
    static dispatch_once_t once;
    static Class *sharedInstance;

    dispatch_once(&once, ^
    {
        sharedInstance = [self new];
    });    
    return sharedInstance;
}