NSBlockOperation addExecutionBlock example ios

addExecutionBlock:

Adds the specified block to the receiver’s list of blocks to perform.

- (void)addExecutionBlock:(void (^)(void))block

Parameters

block

The block to add to the receiver’s list. The block should take no parameters and have no return value.

Discussion of [NSBlockOperation addExecutionBlock]

The specified block should not make any assumptions about its execution environment.

Calling this method while the receiver is executing or has already finished causes anNSInvalidArgumentException exception to be thrown.

Example of [NSBlockOperation addExecutionBlock]

NSBlockOperation *operation = [[NSBlockOperation alloc] init];
__weak NSBlockOperation *weakOperation = operation;
[operation addExecutionBlock:^{
   while( ! [weakOperation isCancelled]){
      //do something...
   }
}];

Example of [NSBlockOperation addExecutionBlock]

NSOperationQueue *operationQueue = [[NSOperationQueue alloc] init];
[operationQueue setMaxConcurrentOperationCount: 1];

NSBlockOperation *operation = [[NSBlockOperation alloc] init];
__weak NSBlockOperation *weakOperation = operation;
[operation addExecutionBlock: ^ {
    for (unsigned i=0; i < 10000000; i++) {
        if ([weakOperation isCancelled]) return;
        printf("%i\n",i);
    }
}];
[operationQueue addOperation:operation];

sleep(1);

if ([operationQueue operationCount] > 0) {
    [operationQueue cancelAllOperations];
}