Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Swift Basics (retired) Control Flow While and Do-While Loop

Tim Hancock
Tim Hancock
3,254 Points
Posted by Tim Hancock
Tim Hancock
3,254 Points

Why does my playground say I can't use a do-while? It says to use a repeat-while?

Can anybody answer this? I don't want to proceed without knowing if I'm doing something wrong.

var todo : [String] = ["Return calls","Write blog","Cook Dinner"]

var index = 0 while index < todo.count{ print(todo[index]) index++ }

index = 0

do { print(todo[index]) index++ } while index < todo.count

I'm following the lesson but my playground won't let me use the do-while. Has anybody experienced this?

Randy Mitchell
Randy Mitchell
2,127 Points
Randy Mitchell
Randy Mitchell
2,127 Points

Do-While is no longer valid syntax and has been replaced with Repeat-While.

e.g.

var todo = ["Practice Coding", "Return Calls", "Cook Dinner"]

var index = 0

repeat {
  print(todo[index])
  index += 1
} while index < todo.count

PS: ++ and -- have also been deprecated. Incrementing and Decrementing are now done with += and -= respectively

2 Answers

agreatdaytocode
agreatdaytocode
24,757 Points

Tim,

The following works fine for me:

var todo : [String] = ["Return calls","Write blog","Cook Dinner"]

var index = 0

while index < todo.count {

    print(todo[index])
    index++
}

Try adding this to your playground. Let me know if it works or not.

Randy Mitchell
Randy Mitchell
2,127 Points
Randy Mitchell
Randy Mitchell
2,127 Points

Tim, he was trying to implement Do-While loop. The example above is just a While loop. Do-While is no longer valid syntax in Xcode 7.3.1 or apparently any versions beyond the the instructors.

Do-While has been replaced with Repeat-While.

e.g.

var todo = ["Practice Coding", "Return Calls", "Cook Dinner"]

var index = 0

repeat {
  print(todo[index])
  index += 1
} while index < todo.count

PS: ++ and -- have also been deprecated. Incrementing and Decrementing are now done with += and -= respectively

Michael Brown
Michael Brown
12,406 Points
Michael Brown
Michael Brown
12,406 Points

Hey Tim, this is because you're running an upgraded version on Xcode 2.3. During this video, they were on 2.1 which had them using do-while. Xcode 2.3 has developers use repeat-while instead which does the same thing.