Question

I’m trying to drop NSOperation objects into an NSOperationQueue. But it seems I’m misunderstanding how to properly initialize an NSInvocationOperation (a subclass that seems tailor-made for my purposes, as I want to execute an existing method inside the operation queue). Here’s what I’m trying:

OnlineServiceManager * sm = [[OnlineServiceManager alloc] initWithAsset:asset andViewController:viewController];
NSInvocationOperation * operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(pushAsset) object:sm];
[queue addOperation:operation];

This stanza is operating within a loop that provides the new asset to be pushed in the operation. As I debug these lines, it turns out that operation is nil, suggesting that the selector can’t be found. The selector is an instance method in this class, with this signature:

- (void)pushAsset

That stanza is also operating in a class method — my intention is to call the class and instruct it to push all assets.

Having searched all the docs I can find relevant to this case, I don’t see quite what I’m doing wrong.

Answer 1

self is the class object and push asset is an instance method, which MIGHT be the issue. What happens if you change push asset to a class method?