Question

I would like to execute code sequentially in an NSOperation.
This can be easily done by instantiating NSInvocationOperation, for example in a controller of mine I have:

NSOperationQueue *queue = [NSOperationQueue new];

NSInvocationOperation *prepare = [[NSInvocationOperation alloc] initWithTarget:self 
                                                                      selector:@selector(prepare) 
                                                                        object:nil];

NSInvocationOperation *load = [[NSInvocationOperation alloc] initWithTarget:self 
                                                                selector:@selector(loadData) 
                                                                        object:nil];

[load addDependency:prepare];

This works perfectly, and most of all I can keep dependency between operations. But as you can see I had to create methods encapsulating the operation itself.
I would like instead to instantiate the invocation as a fragment of code, and keep dependency.
Therefore my view controller would be clean for never again used methods.

I saw there is a ^block option but seems that dependency is not maintained.

thanks

Answer 1

You should be able to add dependencies with any subclass of NSOperation. In your case you probably want NSBlockOperation:

NSOperation *prepare = [NSBlockOperation blockOperationWithBlock:^{
    // code here
}];

NSOperation *laod = [NSBlockOperation blockOperationWithBlock:^{
    // code here
}];

[load addDependency:prepare];