Call Array Where Name is Half String and Half Variable: Dynamic References

Question

My end goal is to pass the desired array to a function. The problem is the array name depends on the situation. It may be 1 of 30 names.

I have about 30 arrays all named "default_SomeName". Now the previous VC passes the SomeName value. Based on that value, my goal is to pass one of the 30 arrays to a function. Yet, dynamic references are apparently not easy.

I've tried:

var someName: String! //Passed from presenting VC
let desiredArray = "default_" + someName
myFunction(desiredArray)

But I get:

Cannot convert value of type 'String' to expected argument type [String]

Anyone know how to do this?

Due to the static nature of Swift, you can only achieve something like this by leaving Swift and going to Obj-C and Foundation methods, using KVO methods of NSObject. Since you're coding in Swift, however, I would advice against this. Possibly change the approach instead; could the "passing VC" pass a simple integer reference instead? Say an Int between 1 and 30 that corresponds to the index in an array of string arrays, [[String]] (which holds your 30 or so String arrays). — dfrib
– dfrib, Commented Feb 13, 2016 at 23:46
You could put the arrays in a dictionary and then you can access the required array by 'name' (key) — Paulw11
– Paulw11, Commented Feb 13, 2016 at 23:51
@Paulw11 - That's interesting... so I make the someName the key and the arrays the thing return? I've never used a dictionary before, never mind for something like that. If you think it'll work, can you post it as an answer? — Dave
– Dave, Commented Feb 14, 2016 at 0:13

Paulw11 · Accepted Answer · 2016-02-14 00:24:25Z

2

You can use a dictionary to associate each dictionary with it's name. Dictionaries are explained in the Apple Swift book, but generally you would do something like this:

var dictionary=[String:[Int]]()

dictionary["default_1234"]=[1,2,3,4]
dictionary["default_5678"]=[5,6,7,8]

let suffix="1234"

print(dictionary["default_\(suffix)"])

In this case I have used an array of Int, but you can have any array type

answered Feb 14, 2016 at 0:24

Paulw11

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4 Comments

Dave Over a year ago

I started reading about them after you mentioned it in the comment. So you're suggested I declare an empty one but set the types. Then, one by one, add a key and the array it should reference. Ultimately, it will allow me to pass the desired array like this?: myFunction(dictionary["SomeKeyName"])

Paulw11 Over a year ago

That's right. It still seems rather clunky, but without knowing more about what you are trying to achieve I can't suggest anything else.

Dave Over a year ago

var dictionary = [String : [String]]() dictionary["Quote"] = defaultNames_Quote - This code is just getting the error 'Expected Declaration' - Maybe I should just use a switch statement? Changing myFunction(desiredArray) depending on the case?

Dave Over a year ago

Marking this correct. I still haven't got it to work, but I'm sure you're right and I just haven't adapted it correctly yet. Might try a switch first.

Dave · Accepted Answer · 2016-02-15 22:22:47Z

Well, since there didn't seem to be an easy way, I decided to go with a sure-fire, clear way!

This switch is as basic as it gets. It takes someName, matches it to a case, and they all run the same function but an array specific to that someName value.

func passArrayToFunc () {
    switch someName {
    case "somename1":
        funcThatNeedsArray(someArray1)
    case "someName2":
        funcThatNeedsArray(someArray2)
    case "someName3":
        funcThatNeedsArray(someArray3)
    case "someName4":
        funcThatNeedsArray(someArray4)
    case "someName5":
        funcThatNeedsArray(someArray5)
    case "someName6":
        funcThatNeedsArray(someArray6)
    case "someName7":
        funcThatNeedsArray(someArray7)
    case "someName8":
        funcThatNeedsArray(someArray8)
    default:
        print("No matches")
    }

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