iOS Store random property in Component e.g. UITextField without Subclass - objective-c

Question

Does anyone know if there is a way to set a property like a string in the User Defined Runtime Atributes sections of Interface Builder without creating a subclass of said component? For example, I want to store a metadata value for each component in my interface that I use later. I just don't want to have to create a subclass or each component to add a metadata property.
This is one approach I came up with. Opinions?
#import <UIKit/UIKit.h>
#import <objc/runtime.h>
#interface UIControl(MetaData)
#property (nonatomic, retain) id entityProperty;
#end
#implementation UIControl(MetaData)
static char const * const EntityPropertyKey = "EntityProperty";
#dynamic entityProperty;
- (id)entityProperty {
return objc_getAssociatedObject(self, EntityPropertyKey);
}
- (void)setEntityProperty:(id)newEntityProperty {
objc_setAssociatedObject(self, EntityPropertyKey, newEntityProperty, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
#end
...
if (textField.entityProperty)
[managedObject setValue: textField.text forKey:textField.entityProperty];

Answer 1

You could keep an NSDictionary somewhere, perhaps in a singleton object that has methods for issuing unique ids for objects and storing metadata by the id keys in the dictionary. The UI objects have a tag property that you can use, if your ids are just incremented integers. Then the dictionary keys would just be NSNumbers for those unique integers.
Like this:
#import <Foundation/Foundation.h>
#interface ACLMetadataManager : NSArray
+(ACLMetadataManager*) sharedMetadataManager;
-(NSUInteger) getUniqueId;
-(void) setObject: (id) object forId:(NSUInteger) theId;
-(id) objectForId:(NSUInteger) theId;
#end
And:
#import "ACLMetadataManager.h"
#implementation ACLMetadataManager { // Private variables
NSMutableDictionary *_metadata;
NSUInteger _ids;
}
- (id)init {
self = [super init];
if (self) {
_metadata = [[NSMutableDictionary alloc] init];
}
return self;
}
+(ACLMetadataManager*) sharedMetadataManager { // Singleton getter
static ACLMetadataManager *instance;
if (instance != nil) {
return instance;
}
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_4_0
static dispatch_once_t oneTimeThread;
dispatch_once(&oneTimeThread, ^(void) {
instance = [[ACLMetadataManager alloc] init];
});
#else
#synchronized(self) {
instance = [[ACLMetadataManager alloc] init];
}
#endif
return instance;
}
-(NSUInteger) getUniqueId { // Increment unique id when getter is called.
return ++_ids; // Start from 1 because tag is 0 by default.
}
-(void) setObject: (id) object forId:(NSUInteger) theId {
[_metadata setObject:object forKey:[NSNumber numberWithInteger:theId]];
}
-(id) objectForId:(NSUInteger) theId {
return [_metadata objectForKey:[NSNumber numberWithInteger:theId]];
}
// Override some methods to ensure singleton stays instantiated.
- (id) retain {
return self;
}
- (oneway void) release {
// Does nothing here.
}
- (id) autorelease {
return self;
}
- (NSUInteger) retainCount {
return INT32_MAX;
}
#end
Usage:
ACLMetadataManager *metadataManager = [ACLMetadataManager sharedMetadataManager];
myControl.tag = [metadataManager getUniqueId];
[metadataManager setObject:myMetadata forId:myControl.tag];