Refactor Help> For loop mapping CGPoints, and SKSpriteNodes

Question 1

Calculating the x coordinate for the position of each node is pretty straightforward:

x starts at 212
Subsequent nodes are 200px to the right of the previous node
Every 5th node is 424px (instead of 200px) to the right of the previous node

The code for that looks like this:

- (SKSpriteNode *)createBottomRack
{
    self.rack = [SKSpriteNode spriteNodeWithColor:[SKColor whiteColor] size:CGSizeMake(10240.0, 200)];
    self.rack.position = CGPointMake(0.0,150.0);
    self.rack.zPosition = 0;
    self.rack.name = @"bottomRack";

    float x = 212.0, y = 0.0;
    for (NSUInteger i = 0; i < 20; i++) {
        SKSpriteNode *dash = [SKSpriteNode spriteNodeWithImageNamed:@"dashedCard"];
        dash.position = CGPointMake(x, y);
        [self.rack addChild:dash];

        // Calculate the next x coordinate
        x += (i % 4 == 3) ? 424.0 : 200;
    }

    return self.rack;
}

Question 2

Since you are new to programming, I suggest you spend some time learning how arrays work, and how they are used:

http://en.wikipedia.org/wiki/Array_data_structure

and their iOS implementation:

https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/NSArray.html

For starters, you can declare two arrays, one containing the SKSpriteNodes, and the other containing the position points:

   //Declare these in @interface
        @property (nonatomic) NSMutableArray *sprites;
        @property (nonatomic) NSMutableArray *points;

    //This will contain the SKSpriteNodes
        self.sprites =[[NSMutableArray alloc] init];

    //This will contain the points, we initialise it with the hard-coded values.
    //You have to wrap the values in an object type of NSValue of the array to accept it
        self.points = [[NSMutableArray alloc] initWithObjects:[NSValue valueWithCGPoint:CGPointMake(212, 0.0)],
                       [NSValue valueWithCGPoint:CGPointMake(412, 0.0)],
                       [NSValue valueWithCGPoint:CGPointMake(612, 0.0)],
                       [NSValue valueWithCGPoint:CGPointMake(812, 0.0)],
                       //Put the rest of the values here... for the moment it will do
                       nil];

    //Now for each declared point, we create a SKSpriteNode, insert it into the array and add it to "rack"

//for will loop over eacg point you have defined.
        for (NSValue *point in self.points){

//This will be a temporary object we create to add it into the array.
            SKSpriteNode *node =[SKSpriteNode spriteNodeWithImageNamed:@"dashedCard"];
            node.position = [point CGPointValue];
            [self.sprites addObject:node];
            [self.rack addChild:node];
        }

As you get more experience you will find many other ways to improve the code, but take your time studying the code and basic data structures. Good luck!