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iOS Swift 2.0 Collections and Control Flow Control Flow With Loops For In Loops

Posted by Mitchell Warmerdam
Mitchell Warmerdam
4,225 Points

Make sure the results array contains the first 10 multiples of 6

I'm stuck at the point where I'm asked to create append the results of a value by creating a loop. The array has to contain the first 10 multiples of 6. This is my query and I don't understand why it's not working. Your help would be much appreciated ;)

Thanks,

var results: [Int] = [1,2,3,4,5,6,7,8,9,10]

for multiplier in 1...10 { results.append(multiplier * 6) }

5 Answers

Michael Reining
Michael Reining
10,101 Points
Michael Reining
Michael Reining
10,101 Points

Hi Mitchell,

I would break it down.

Step 1: Create a loop that iterates 10 times and name the constant multiplier

for multiplier in 1...10 {
}

Step 2: Multiply the value by 6 and add it to the results array.

var results: [Int] = []

for multiplier in 1...10 {
    let result = multiplier * 6
    results.append(result)
}

The initial array should definitely be left empty. You specify how often to run a loop by using 1...X where X is the number of times you want to run the loop.

I hope that helps,

Mike

PS: Thanks to the awesome resources on Team Treehouse, I just launched my first app. :-)

Code! Learn how to program with Swift

Michael Reining
Michael Reining
10,101 Points
Michael Reining
Michael Reining
10,101 Points

Have you tried to complete the challenge by leaving the initial array empty? That should definitely do the trick.

Mitchell Warmerdam
Mitchell Warmerdam
4,225 Points
Mitchell Warmerdam
Mitchell Warmerdam
4,225 Points

Hi Michael,

Thanks for helping out. I understand what you mean and I tried your solution but it still tells me "Your array needs to contain the first 10 multiples. Make sure your range goes from 1 to 10". Stefan, your explanation also makes sense now, I see what I am doing wrong but I'm still not able to find the solution. Hope you guys can still help me out here.

Thanks! Mitchell

var results: [Int] = [1,2,3,4,5,6,7,8,9,10]

for multiplier in 1...10 {
    let result = multiplier * 6
    results.append(result)
}
Stefan Cimander
Stefan Cimander
37,115 Points
Stefan Cimander
Stefan Cimander
37,115 Points

The only problem in your code is, that still your results array does contain too many values at the end. You don't need to write

var results: [Int] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Instead, you should start with an empty array, that is only filled within the for-loop.

var results: [Int] = []

The rest of your code works perfectly fine.

Stefan Cimander
Stefan Cimander
37,115 Points
Stefan Cimander
Stefan Cimander
37,115 Points

Implementing your approach, the final results array looks like this after executing the loop: results = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60]

Instead, make sure to start with an empty results array.

I'm not sure, why you are instantiating the results array with the values from 1 to 10. I guess you kind of think that you need it for the loop condition, but therefore, the range operator 1...10 is used. So, there is really no need to start with a non-empty results array.

Hope this helps.

Mitchell Warmerdam
Mitchell Warmerdam
4,225 Points
Mitchell Warmerdam
Mitchell Warmerdam
4,225 Points

You are right! I finally completed the challenge with your help. Thanks a lot, I appreciate it

Cheers, Mitch