Using instance variable from NSArray of objects
Using instance variable from NSArray of objects
- Subject: Using instance variable from NSArray of objects
- From: Steve Gran <email@hidden>
- Date: Fri, 9 Dec 2005 00:26:55 -0800
I'm a real Newbie so I hope I explain this well enough. I'm trying
to access a variable of an array of objects and because I'm so new to
programming in general (not just Cocoa) I just don't get why this is
not working.
Basically I have an NSArray that (using NSArrayController and
bindings) I have in a tableview. Everything works fine except when I
try to access one of the variables which happens to be an integer type.
So for example, my class Cars has three instance variables (NSString
carMake, NSString carModel, int priceOfCar). An NSArray
myArrayOfCars holds the Cars objects (myCar1, myCar2, myCar3, etc.).
For this example let's just say the values of myCar2 are:
carMake = BMW
carModel = 530i
priceOfCar = 55000
I'd like to:
1) search through the array to find a particular carModel, then
2) return the value of priceOfCar to be used in a calculation
I was shown how (using predicates, thanks mmalc) I can filter the
array as follows:
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"carModel
like '530i'"];
theObjectINeed = [myArrayOfCars filteredArrayUsingPredicate:predicate];
And yes, sure enough, theObjectINeed is myCar2 (I can tell using
NSLog). Which is great because I'm probably going to use different
predicates depending on certain situations and thus won't know in
advance it's myCar2 I need to find. But then when I try the following:
returnedPrice = [theObjectINeed valueForKey:@"priceOfCar"];
I don't get what I expect. And if I try to have returnedPrice sent
to a NSTextView by doing the following:
[returnedPrice setIntValue: [theObjectINeed valueForKey:@"priceOfCar"]];
I get a Warning Message that says "makes integer from pointer without
a cast". But the priceOfCar instance variable is an int and was
declared as such. What am I doing wrong? I mainly want to be able
to use that variable in some calculations so I do want it to be an
integer.
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