iOS - Can't add NSString objects to NSMutableSet - ios

Question

For some reason NSString objects just won't go into an NSMutableSet
The set remains empty - count stays 0 and firstInHandler is never called
I have tried everything..!
If anyone has any idea why I would greatly appreciate the help
VCKeySet.h
#import <Foundation/Foundation.h>
#interface VCKeySet : NSObject
{
void (^firstInHandler)();
void (^lastOutHandler)();
}
#property (atomic, readonly, strong) NSMutableSet* keys;
- (id) initWithFirstInHandler:(void(^)()) firstInHandler_ withLastOutHandler:(void(^)()) lastOutHandler_;
- (void) add:(NSString*) key_;
- (void) remove: (NSString*) key_;
- (BOOL) has: (NSString*) key;
#end
VCKeySet.m
#import "VCKeySet.h"
#implementation VCKeySet
#synthesize keys;
- (id) initWithFirstInHandler: (void(^)()) firstInHandler_ withLastOutHandler: (void(^)()) lastOutHandler_
{
if(self=[self init])
{
firstInHandler = firstInHandler_;
lastOutHandler = lastOutHandler_;
}
return self;
}
- (void) add:(NSString*) key_
{
for(NSString* key in self.keys)
{
if([key isEqualToString:key_])
{
return;
}
}
[self.keys addObject:key_];
if([self.keys count] == 1)
{
firstInHandler();
}
}
- (void) remove: (NSString*) key_
{
for(NSString* key in keys)
{
if([key isEqualToString:key_])
{
[keys removeObject:key];
if([keys count] == 0)
{
lastOutHandler();
}
}
}
}
- (BOOL) has: (NSString*) key_
{
for(NSString* key in keys)
{
if([key isEqualToString:key_])
{
return YES;
}
}
return NO;
}
#end
Here is how I try to add a key to the set
VCKeySet* lock = [[VCKeySet alloc] initWithFirstInHandler:^()
{
NSLog(#"Adding UI lock");
[application beginIgnoringInteractionEvents];
}
withLastOutHandler:^()
{
NSLog(#"Removing UI lock");
[application endIgnoringInteractionEvents];
}];
[lock add:#"InitialiseApp"];
Thanks

Answer 1

The problem is, you never allocate and initialize your set.
Refactor your add: method to look something like this:
- (void) add:(NSString*) key_ {
if (!self.keys) {
_keys = [[NSMutableSet alloc] init];
}
[self.keys addObject:key_];
if([self.keys count] == 1) {
firstInHandler();
}
}