CODEWITHSUNDEEP
objective-ciosfor-loop
Jason
Jason

Reputation: 171

For loop that will give me objects at index: 0,1 then 1,2 then 2,3 then 3,4 following this pattern until array count?

I've been trying to get these results for a while now.. I can't seem to figure it out. Anyone know how to go about doing this?

I'm trying to compare two objects to each other from the beginning of my array, to the end, in that sequence.

Tilo's Solution:

        for (int i=1; i<[tempRightArray count]; i++) {
            UIImageView* letterA = [tempRightArray objectAtIndex:i-1];
            UIImageView* letterB = [tempRightArray objectAtIndex:i];

            NSLog(@"LetterA: %@",letterA);
            NSLog(@"LetterB: %@",letterB);

            //Distance between right side of Touched piece and Left side of new piece == Touch on Right
            CGPoint midPointRightSidePiece = CGPointMake(CGRectGetMaxX(letterA.frame), CGRectGetMidY(letterA.frame));
            CGPoint midPointLeftSidepiece = CGPointMake(CGRectGetMinX(letterB.frame), CGRectGetMidY(letterB.frame));
            CGFloat distance = DistanceBetweenTwoPoints(midPointLeftSidepiece, midPointRightSidePiece);

            NSLog(@"Distance: %f",distance);

        }

Updated with Pauls block solution:

    [tempRightArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

        if (idx > 0) {

            UIImageView *letterB = (UIImageView*)obj;

            id obj2 = [tempRightArray objectAtIndex:--idx]; // idx is the index of obj again given to you by the block args

            UIImageView *letterA = (UIImageView*)obj2;

            NSLog(@"LetterA: %@",letterA);
            NSLog(@"LetterB: %@",letterB);

            //Distance between right side of Touched piece and Left side of new piece == Touch on Right
            CGPoint midPointRightSidePiece = CGPointMake(CGRectGetMaxX(letterA.frame), CGRectGetMidY(letterA.frame));
            CGPoint midPointLeftSidepiece = CGPointMake(CGRectGetMinX(letterB.frame), CGRectGetMidY(letterB.frame));
            CGFloat distance = DistanceBetweenTwoPoints(midPointLeftSidepiece, midPointRightSidePiece);

            NSLog(@"Distance: %f",distance);

        }

    }];

Upvotes: 0

Views: 284

Answers (5)

NSResponder
NSResponder

Reputation: 16861

Don't forget that Objective-C is a superset of C. Anything you can do in C, you can still do in Obj-C.

You probably weren't aware of the comma operator. You can execute multiple operations in each clause of a for(;;) loop.

NSUInteger limit, i, j;

for(limit = [array count], i = 0, j = 1; j <= limit; i++, j++)
  {
  //  i and j will increment until j hits the limit.   
  // do whatever you want with [array objectAtIndex:i] and [array objectAtIndex:j] in here.
  }

Upvotes: 0

Paul.s
Paul.s

Reputation: 38728

How about something like this?

  NSArray *array = [NSArray arrayWithObjects:@"a", @"b", @"b", @"c", @"d", nil];

  [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

    if (idx > 0) {
      // obj  = the current element in the array. Given to you by the block args
      id obj2 = [array objectAtIndex:--idx]; // idx is the index of obj again given to you by the block args

      // Do whatever comparison you want between obj and obj2
      // ...
    }

  }];

Don't be scared by the syntax its pretty simple. The current object is obj and the index of that object in the array is idx.

Upvotes: 2

tilo
tilo

Reputation: 14169

for (int i=1; i<[myArray count]; i++) {
  id obj1 = [myArray objectAtIndex:i-1];
  id obj2 = [myArray objectAtIndex:i];

  [self compare:obj1 to:obj2];
}

Upvotes: 2

AusCBloke
AusCBloke

Reputation: 18512

for (i = 0; i < array_count - 1; i++) {
   x = array[i];
   y = array[i + 1];
   /* do something with x and y */
}

Where array is the array, array_count is the length of array, x and y are declared as the same type as the elements stored in array. Is this what you're asking for?

Upvotes: 0

Jim Rhodes
Jim Rhodes

Reputation: 5095

Start the for loop with your index at one. Stop when the index is greater than or equal to array count. Compare item at index and at index - 1;

Upvotes: 0

Related Questions