Question

I want to get variable value from an objective-c class, using reflection.

company.h looks like

@interface Company : NSObject {
}
@property (nonatomic, retain) NSString* phone;
- (NSString*) getPropertyValueByName: (NSString*) paramName;

company.m looks like

@implementation Company
@synthesize phone;
- (NSString*) getPropertyValueByName: (NSString*) paramName
{    
    id me = self;
    value = [me objectForKey: paramName];
    return value;
}
@end

I am using this like:

Company* comp = [Company new];
comp.phone = @"[phone]";

NSString* phone = comp.getPropertyValueByName(@"phone");

What I am getting is an exception:

-[Company objectForKey:]: unrecognized selector sent to instance

Answer 1

That should be valueForKey instead of objectForKey. objectForKey is an NSDictionary instance method.
Besides that there’s a potentional mistake in your code. Your return type in the above method is string but you don’t cast it to NSString before returning.Even if you’re sure that it’ll always return a string it’s good practice to avoid any doubts. And when declaring an NSString property you should copy it rather than retaining it. And, what’s the point in declaring a “me” variable if you can easily say:

[self valueForkey:paramName];