AFNetworking is Asynchronous, you have to place the log inside the success block. Otherwise the array will always be empty.
One good solution would be to pass a block to your getImages function like that
-(void) getImages:(void (^)(BOOL result))callback {
// your code here then you call callback(YES or NO) inside your success or failure block.
}
[self getImages:^(BOOL result){
if(result)
//we got the images, we can now display them etc.
}];