newbie question on array subsets

[digitaldust]

Hello List,

I have a simple question, but I cannot solve it. Suppose you have a NSMutableArray like in TheElements example app. You fill it with

NSString *thePath = [[NSBundle mainBundle] pathForResource:@"Elements" ofType:@"plist"];
NSMutableArray *newArray = [[NSArray alloc] initWithContentsOfFile:thePath];

suppose you want to subset the array using only the elements in the plist with state = Solid

what is the right sintax to do that?

many thanks,
simone

[smasher]

"filteredArrayUsingPredicate" will do that for you:

NSArray Class Reference

Otherwise you could loop through the original array, and add just the items that pass your test to a new array.

[digitaldust]

well I was thinking about something like

NSArray *filteredElementArray = [newArray valueForKey:@"state"];

but I didn't know how to specify the condition state = Solid

I'll try to use filteredArrayUsingPredicate, as soon as I understand its sintax...

many thanks for your reply,
simone

[digitaldust]

I am trying this, but it doesn't seem to work properly:

// read the element data from the plist
NSString *thePath = [[NSBundle mainBundle] pathForResource:@"Elements" ofType:@"plist"];
// build an array with the plist
NSMutableArray *newArray = [[NSArray alloc] initWithContentsOfFile:thePath];
// build a predicate to filter the array
NSPredicate *Predicate = [NSPredicate predicateWithFormat:@"SELF contains[c] 'Solid'"];
// filter the array with the predicate
NSArray *rawJewelsArray =[newArray filteredArrayUsingPredicate:Predicate];

Where am I doing something wrong? I suppose SELF is not the right keyword, but how to specify the "state" condition?

best regards,
simone

[digitaldust]

I've also seen this post No NSPredicate on iPhone, How do I filter an NSMutable Array? - Mac Forums

does NSPredicate works on iphone device?

thanks,
Simone

[smasher]

Ah, I'm very sorry. I didn't try NSPredicate, and didn't know it's missing on the iPhone.

You'll have to build a second array instead:

NSMutableArray *filteredArray = [[NSMutableArray alloc] init]

for (id item in rawJewelsArray){
     if (item.solid)
          [filteredArray addObject: item];
}

You can replace "id" with "Jewel *" or the real type of your objects.

[digitaldust]

Originally Posted by smasher

Ah, I'm very sorry. I didn't try NSPredicate, and didn't know it's missing on the iPhone.

You'll have to build a second array instead:

NSMutableArray *filteredArray = [[NSMutableArray alloc] init]

for (id item in rawJewelsArray){
     if (item.solid)
          [filteredArray addObject: item];
}

You can replace "id" with "Jewel *" or the real type of your objects.

I see... many thanks for the code example!!!

best regards,
Simone