Build Your Swift Skills - Lesson 7 - Loops

Alright, so now you know how to store collections of data using Arrays and Dictionaries.

What if you need to write code to do something with each piece of data in the collection?

For example, let’s say you need to give each employee in the company database a salary raise? (Yeah, right!)

Well, we had better learn about Loops to make that happen!

Loops come in handy to let you go through each item in the collection and execute some code for each!

Finally, don't forget to download the worksheet below to get extra practice!

To download the code, projects, worksheets and assets, visit:

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DID THESE LESSONS HELP YOU?

[chargeflood]

Have finished your 2 courses(part 1 and part 2) patiently and that was brilliant. Nice job Chris.

[imladenov]

you are literally the best teacher ever, thank you so much I support your channel and am subscribed with notifications turned on. I will be purchasing your swift courses soon! :)

[dcskinner]

Oh, it would also be a good tip to show how to break an infinite loop in the playground while it is running. It wasn't immediately obvious that you can type "break" in the loop while it is going to stop it. I find it useful and fun to pause the lesson just after you describe what you are going to do and tried it on my own and then see how close I get.

[ThePepefl]

Thank you Chris I am learning a lot with your videos.

[christopherjschultz]

Great Lessons I really enjoyed these videos! Awesome Job!

[MorganMath]

Having lots of fun learning Swift and using the Xcode IDE!
Regarding the randomization of the array at time 19:42, like @Dennis_Skinner mentioned the loop goes 15 times to fill 10 random numbers (some iterations produce duplicates and are "extra" iterations). I tried a way to guarantee only 10 iterations for 10 items (and also learned how to identify an object type and create an array of some unknown type of another object). Here is code for Swift 3.0.2 (and probably higher):

// Some pre-populated array of any type (this examples is [String]...
var prePopListArray = ["Albert", "Bob", "Camille", "Donald", "Eugene"]
print("Pre-populated array items: \(prePopListArray)")


// Creates an array of the same data type as the prePopListArray...
var randArray =


/* Loops through and grabs a random item out of the prePopListArray and adds it to the randArray. Then deletes that item out of the prePopListArray (so not to have duplicates) and grabs another random from the remaining in prePopListArray. This guarantees to loop only as many times as the size of your prePopListArray. Works for an array of any data type.
*/
while prePopListArray.count > 0 {
let randNum =

prePopListArray.remove(at: randNum)
}
print("Randomized array items: \(randArray)")

Time to play in the next lesson!

[hudsoncurren]

20:11 lagged the fuck out of my computer because apparently, it needs to try over 15, 000 times. FIX IT APPLE. Also good stuff bro its been hard to convince myself to do this and you have made it interesting

[dcskinner]

Lots of good info. FYI, it says how many times the loop ran in the right side of the Playground. Thanks, again!

[allin]

Nice. Thanks again....waiting for next.

[chocoHB]

FYI: "repeat {} while count < 10" will give a different result than "while count < 10 {}". 
The first will give 10 values. The second one with the while first will give only 9 values. 
Try it in Playground to verify.

[brandonmclaughlin]

Hi All. I cant seem to get rid of this error. I'm pretty sure I have it typed out exactly how it is in the lesson. Maybe my brain is starting to get hazy! Can anyone see a problem?

error is "Argument passed to call that takes no arguments"



//Fill an array with 10 ransom numbers in the range of 1-10. Duplicates are OK


for _ in 1...10 {

let randomNumber = arc4random(10) + 1

// array += [randomNumber]

print(randomNumber)

}

[michaelandersen]

Nice stuff...! Weird, I just saw a blue screen 'while' expecting to see some text about "while" loops... (reminiscent of Windows, heh heh...)

[dwinosam]

I'm assuming Xcode already knows how to identify animals from a database in a super class? Otherwise, how does it know?

[TheCSteve]

This module 2 was more complex as i thought.. I hope i can remember this all .. But thanks again

[eliseerickson]

Love your stuff man! I know Java so I ran through your videos to teach myself Swift. I have one question? Where do I write my classes in Xcode? AppDelegate, RootViewController, DataViewController, or ModelController? Thank you!