Avoid Object Being Deallocated Without Adding Property/iVar to UIViewController

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/