iOS Arrays with custom classes to arrays with NSStrings

Question

I have my own class with several properties and I have them in NSArray. I need to use them for method which takes NSArray of strings. So I am asking what is best aproach to get array with strings from my array which has custom classes. I can create second array and use it but I think there could be better way. I need to have it for different custom classes (from one, I want to use for example name property to new NSArray, in second title property and so).

I hope I explained well but I tried it once more on example:

NSArray *arrayWitCustomClasses =  ... fill with custom classes;
// setValues method takes NSArray with NSStrings
// when arrayWithCustomClasses used it returns copyWithZone: error on custom class
[someObject setValues:[arrayWithCustomClasses toArrayWithStrings]];

Paulw11 · Accepted Answer · 2014-08-12 10:22:07Z

3

As long as your object exposes the required values as NSString properties you can use the valueForKey method of NSArray.

For example

NSArray *arrayOfTitles=[arrayWithCustomClasses valueForKey:@"title"];

NSArray *arrayOfNames=[arrayWithCustomClasses valueForKey:@"name"];

Or

[someObject setValues:[arrayWithCustomClasses valueForKey:@"title"]];

and so on

edited Aug 12, 2014 at 10:22

answered Aug 12, 2014 at 10:17

Paulw11

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3 Comments

Trenskow Over a year ago

I might be wrong, but I think you need to use valueForKeyPath: ?

Paulw11 Over a year ago

valueForKey: Returns an array containing the results of invoking valueForKey: using key on each of the array's objects.

Libor Zapletal Over a year ago

This is what I was looking for. It's a little better then @Trenskow because I can use properties with valueForKey.

cutsoy · Accepted Answer · 2014-08-12 10:11:56Z

2

NSMutableArray *strings = [NSMutableArray array];

for (NSObject *item in arrayWithCustomClasses) {
    /* You can use a different property as well. */
    [strings addObject:item.description];
}

[someObject setValues:strings.copy];

answered Aug 12, 2014 at 10:11

cutsoy

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Comments

Trenskow · Accepted Answer · 2014-08-12 10:20:50Z

2

Like @Tim says, but you could shorten it by just using:

[someObject setValues:[arrayWithCustomClasses valueForKey:@"description"]];

Same result. One line of code.

Then implement the description method of your custom classes to return whatever properties and formatting you want.

edited Aug 12, 2014 at 10:20

answered Aug 12, 2014 at 10:14

Trenskow

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