execute task with a time sequence in iOS

Question

I want to execute some codes with a time sequence like [5s, 10s, 10s, 20s], which means that it executes the code after 5 seconds, and executes it the second time after 10s. I want to use NSTimer, but I can not figure out how can I do.

Answer 1

My method is a bit simpler to implement.

- (void)startExecute
  { 
    intervals=@[@(5),@(10),@(10),@(20)]; // class member
    isExecuting=YES; // class member
    [self executeTaskAtIndex:0]; // start first task
  }

- (void)executeTaskAtIndex:(NSUInteger)index
  { 
   if (index>=intervals.count || !isExecuting) // no intervals left or reset execution
       return;
   NSNumber *intervalNumber=intervals[index];
   NSTimeInterval interval=intervalNumber.doubleValue;
   dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(interval * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
      if(!isExecuting)
         return;
      // execute your task here
      //...
      index++;
      [self executeTaskAtIndex:index]; // another iteration
   });
  }