Force deletion of singleton in test code that was created with dispatch_once

Question

I\'m writing some unit test code for a model class and want to simulate the behavior of the class during app exit and relaunch. I could achieve this by deleting and re-allocing

Answer 1

static MyModel *singleton = nil;
static dispatch_once_t onceToken;

+ (instancetype) sharedInstance
{
    dispatch_once(&onceToken, ^ {
        if (singleton==nil){
            singleton = [[MyModel alloc] initSharedInstance];
        }
    });
    return singleton;
}

+(void)setSharedInstance:(MyModel *)instance {
    onceToken = 0;
    singleton = instance;
}

Nil it:

[MyModel setSharedInstance:nil];

Note that you can also set it to an arbitrary class to mock it.

[MyModel setSharedInstance:someMock];