iOS - How to know when NSOperationQueue finish processing a few operations?
download, ios, ipad, iphone, nsoperation
Solution
Add a "Done" `NSOperation` which has all other `NSOperations` for one directory as dependency.
Something like this:
NSInvocationOperation *doneOp = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(done:) object:nil];
NSInvocationOperation *op1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(doSomething:) object:nil];
[queue addOperation:op1];
[doneOp addDependency:op1];
NSInvocationOperation *op2 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(doSomething:) object:nil];
[queue addOperation:op2];
[doneOp addDependency:op2];
NSInvocationOperation *op3 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(doSomething:) object:nil];
[queue addOperation:op3];
[doneOp addDependency:op3];
[queue addOperation:doneOp];
`doneOp` will only run after `op1`, `op2` and `op3` have finished executing.
Problem
I need in my application to download directories and their content. So I decided to implement a NSOperationQueue and I subclassed NSOperation to implement NSURLRequest etc... The problem is I add all the operations at once and I can't figure out when all the files for one directory are downloaded in order to update the UI and enable this specific directory. Now I have to wait that all the files from all the directories are downloaded in order to update the UI. I already implemented key-value observing for the operationCount of the NSOperationQueue and the isFinished of the NSOperation but I don't know when a directory has all the files in it ! Do you have any idea ? Thanks a lot