Avoid Object Being Deallocated Without Adding Property/iVar to UIViewController - ios

Question

I have a custom class/object that handles gestures and conducts animations for a given view using a CADisplayLink. In its simplest form my class looks something like follows:
#interface SomeClass : NSObject
#property (strong) UIView *someView;
#end
When I add the following code to my view controller....
- (void)viewDidLoad
{
[super viewDidLoad];
SomeClass *someClass = [[SomeClass alloc] init];
someClass.someView = someView;
}
... I was anticipating my someClass object would be retained for the life of the view controller, since I am using a strong reference to someView.
However someClass is immediately deallocated.
I am already aware that I can overcome the deallocation simply by adding someClass as a property (or indeed iVar) of the view controller however I would ideally like to avoid this extra work...
so is there anyway I can have my class retained until either the view or view controller its associated with are deallocated?
EDIT
UIGestureRecognizer objects are an exmaple of a class that doesn't get deallocated when I associate them with a view...
- (void)viewDidLoad
{
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] init];
[someView addGestureRecognizer:gestureRecognizer];
}
// tapGestureRecognizer still lives
Presumably this is because the UIView takes owner ship of the UIGestureRecognizer object. Is there anyway to achieve this with my class and a UIView category? I.e....
- (void)viewDidLoad
{
[super viewDidLoad];
SomeClass *someClass = [[SomeClass alloc] init];
[someView addSomeClass:someClass];
}

Answer 1

If you want to associate the object with a UIView in the same way a UIGestureRecognizer does then this is technically possible using associatedObjects as follows (but I'm not sure I'd advocate this approach since associatedObjects are often frowned upon)...
SomeClass.h
#class SomeClass;
#interface UIView (SomeClass)
- (void)addSomeClass:(SomeClass *)someClass;
- (void)removeSomeClass:(SomeClass *)someClass;
#end
#interface SomeClass : NSObject
#property (strong) UIView *someView;
#end
SomeClass.m
#import "SomeClass.h"
#import <objc/runtime.h>
#implementation UIView (AssociatedObject)
- (void)addSomeClass:(SomeClass *)someClass
{
NSMutableArray *someClasses = [self someClasses];
if (someClasses == nil) {
someClasses = [[NSMutableArray alloc] init];
[self setSomeClasses:someClasses];
}
[someClasses addObject:someClass];
}
- (void)removeSomeClass:(SomeClass *)someClass
{
NSMutableArray *someClasses = [self someClasses];
if (someClasses != nil) {
[someClasses removeObject:someClass];
if (someClasses.count == 0) {
[self setSomeClasses:nil];
}
}
}
#pragma mark - Private Methods
- (NSMutableArray *)someClasses
{
return (NSMutableArray *)objc_getAssociatedObject(self, #selector(someClasses));
}
- (void)setSomeClasses:(NSMutableArray *)someClasses
{
objc_setAssociatedObject(self, #selector(someClasses), someClasses, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
#end
#implementation SomeClass
#end
Implementation
- (void)viewDidLoad
{
[super viewDidLoad];
SomeClass *someClass = [[SomeClass alloc] init];
someClass.someView = someView;
[someView addSomeClass:someClass];
}
Some further reading on associatedObjects from NSHipster...
http://nshipster.com/associated-objects/

Answer 2

But you can declare SomeClass instance instead of property like this:
#implementation ViewController
{
SomeClass* _someClass;
}
...
- (void)viewDidLoad
{
[super viewDidLoad];
_someClass = [[SomeClass alloc] init];
_someClass.someView = someView;
}

Answer 3

Your SomeClass instance is holding a strong reference to the someView, but nothing is holding a reference to the SomeClass instance except the local variable inside your viewDidLoad message, so as soon as the method exits, that instance can be deallocated. As that was the object holding the only reference to your UIView the view can also be deallocated.
Your only options are to store the reference to the SomeClass object in an instance variable (or iVar) as stosha suggested or in a property. Properties are the preferred method and with automatic synthesis they don't take much more effort than a local variable declaration.
You can declare the property inside the .m file so that it isn't visible to other classes that reference your ViewController class -
In your ViewController.m file -
#interface ViewController ()
#property (strong, nonatomic) SomeClass *someClass;
#end
#implementation ViewController
...
(void)viewDidLoad
{
[super viewDidLoad];
self.someClass = [[SomeClass alloc] init];
self.someClass.someView = someView;
}