Casting Syntax to Loop Through Array of Arrays in Swift

Question

I have an NSArray consisting of NSArrays of strings created in Objective-C.

I now want to loop through the items in the array in a swift class and am having trouble with the syntax.

The original Objective-C Array of arrays looks like the following:

NSArray* shapes =@[@[@"square",@"square.png"],@[@"circle",@"circle.png"],@[@"square",@"square.png"]];

I am able to get and print the Array from the Objective-C class using:

let shapes:Array = Utilities.sharedInstance().getShapes

The following to loop through the array, however, is not compiling:

var term : String = ""
var pic : String = ""
for shape in shapes  {
term  = shape[1] //ERROR HERE
pic = shape[2] //SAME ERROR HERE
            }

It gives the error: Type 'Any' has no subscript members

What is the proper syntax to loop through the elements?

Shehata Gamal · Accepted Answer · 2018-12-16 20:07:18Z

2

You can try

 let shapes = Utilities.sharedInstance().getShapes as! [[String]]

Your Array elements are of type Any so you can't use [] with them until you cast , it's always the case when you use bridged code from objective-c , so you have to be specific about the actual type you use , also i encourage

struct Item {
   let term,pic:String
}

Then

let res:[Item] = shapes.map { Item(term:$0[0],pic:$0[1]) }

an irrelevant note but important you can do

NSArray* shapes = @[@"square",@"circle",@"square"];

then the matter of appending .png is simple instead of having an [[String]] directly it's [String]

edited Dec 16, 2018 at 20:07

answered Dec 16, 2018 at 19:50

Shehata Gamal

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3 Comments

user1904273 Over a year ago

This is a sidenote, but apparently the first element of an array in swift is [1] as opposed to [0]?

Shehata Gamal Over a year ago

swift array indexing is zer0-based also , for your case you can easily test it with shape[2] and it will crash the app with index-out of range exception

user1904273 Over a year ago

OK. That makes more sense.

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