CODEWITHSUNDEEP
iosnsoperationnsoperationqueue
user2984254
user2984254

Reputation: 109

getting value from a NSBlockOperation?

hi guys im very frustrated because i want to improve a code but i'm not getting good results this is my piece of code 

NSBlockOperation *blockOperation1 = [NSBlockOperation blockOperationWithBlock: ^{
        value1 = [self getDiferences:0.0 finx:width iniy:0.0 finy:cuartoheith image:imagen1 imagetoComapare:imagen2];
    }];
    [queue addOperation:blockOperation1];

NSBlockOperation *blockOperation2 = [NSBlockOperation blockOperationWithBlock: ^{
        value2 = [self getDiferences:0.0 finx:width iniy:0.0 finy:cuartoheith image:imagen1 imagetoComapare:imagen2];
    }];
    [queue addOperation:blockOperation2];

NSBlockOperation *blockOperation3 = [NSBlockOperation blockOperationWithBlock: ^{
        value3 = [self getDiferences:0.0 finx:width iniy:0.0 finy:cuartoheith image:imagen1 imagetoComapare:imagen2];
    }];
    [queue addOperation:blockOperation3];

NSBlockOperation *blockOperation4 = [NSBlockOperation blockOperationWithBlock: ^{
        value4 = [self getDiferences:0.0 finx:width iniy:0.0 finy:cuartoheith image:imagen1 imagetoComapare:imagen2];
    }];
    [queue addOperation:blockOperation4];

i want use this values outside the NSBlockOperation like this valuetotal=value1+value2+value3+value4; please help or help with a better solution

Upvotes: 2

Views: 741

Answers (2)

limboy
limboy

Reputation: 4089

one block operation is enough, cause it is able to add more blocks, and execute concurrently, meanwhile provide a block to trigger when all blocks are completed, like this:

NSMutableArray *array = [[NSMutableArray alloc] init];
NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
    [array addObject:@"op1"];
}];
[operation addExecutionBlock:^{
    [array addObject:@"op2"];
}];

[[[NSOperationQueue alloc] init] addOperation:operation];
[operation setCompletionBlock:^{
    NSLog(@"array:%@", array);
}];

Upvotes: 0

Léo Natan
Léo Natan

Reputation: 57040

Add another operation which is dependent on your other operations (using addDependency:), and add your code there. Queue this operation. It will wait for all others to finish, and then use their output.

For example,

NSBlockOperation *blockOperationFinal = [NSBlockOperation blockOperationWithBlock: ^{
    valueTotal = value1 + value2 + value3 + value4;
}];

[blockOperationFinal addDependency:blockOperation1];
[blockOperationFinal addDependency:blockOperation2];
[blockOperationFinal addDependency:blockOperation3];
[blockOperationFinal addDependency:blockOperation4];

[queue addOperation:blockOperationFinal];

Upvotes: 3

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