ArrayDemo.m

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 1;
NSInteger inputValue = 5;

NSMutableArray<NSOperation *> *operations = [NSMutableArray<NSOperation *> array];
for (NSInteger i=0; i<inputValue; i++){
    NSOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@".Running operation %d", i);
        [NSThread sleepForTimeInterval:1];
    }];
    [operations addObject: operation];
}

[operations[1] addDependency:operations[2]];
[queue addOperations: operations waitUntilFinished:NO];