#JLTContextInfo

A simple way to add extra data to any object (as long as it’s derived from NSObject).

##Basic Use

Unlike lots of Objective-C old schoolers, I really like dot-property and subscripted key syntax. Here I'll save a little extra data to object.

object.JLT_contextInfo[@"extra"] = data;

Later on, I can get that extra data back.

id savedData = object.JLT_contextInfo[@"extra"];

If you define JLT_SHORTHAND in your project -Prefix.pch, then you can leave off the JLT_ part.

object.contextInfo[@"extra"] = data;

##Improving UIAlertView

There have been a couple of times when having some context info has cut down on the number of properties I've needed to store in my view controllers. Here I can change the text of any button to magic without having to save it out as it's own separate property.

- (IBAction)buttonTextToMagic:(UIButton *)button
{
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Make Magic"
                                                        message:@"Do you want to make the button title \"Magic\"?"
                                                       delegate:self
                                              cancelButtonTitle:@"NO"
                                              otherButtonTitles:@"YES", nil];

    alertView.contextInfo[@"button"] = button;
    [alertView show];
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex != alertView.cancelButtonIndex) {
        UIButton *button = alertView.contextInfo[@"button"];
        [button setTitle:@"Magic" forState:UIControlStateNormal];
    }
}

##Unit Tests for JLTContextInfo

JLTContextInfo passes the following unit tests.

- (void)testContextInfo
{
  NSObject *object = [[NSObject alloc] init];
  NSMutableDictionary *contextInfo = [object JLT_contextInfo];
  STAssertNotNil(contextInfo, nil);
  STAssertTrue([contextInfo isKindOfClass:[NSMutableDictionary class]], nil);
}

#if defined(JLT_SHORTHAND)
- (void)testContextInfoShorthand
{
  NSObject *object = [[NSObject alloc] init];
  NSMutableDictionary *contextInfo = [object contextInfo];
  STAssertNotNil(contextInfo, nil);
  STAssertTrue([contextInfo isKindOfClass:[NSMutableDictionary class]], nil);
}
#endif

- (void)testContextInfoSaveString
{
  NSObject *object = [[NSObject alloc] init];
  [[object JLT_contextInfo] setObject:@"Test String" forKey:@"saved"];

  NSString *saved = [[object JLT_contextInfo] objectForKey:@"saved"];
  STAssertEqualObjects(saved, @"Test String", nil);
}

- (void)testContextInfoAsProperty
{
  NSObject *object = [[NSObject alloc] init];
  NSMutableDictionary *contextInfo = object.JLT_contextInfo;
  STAssertNotNil(contextInfo, nil);
  STAssertTrue([contextInfo isKindOfClass:[NSMutableDictionary class]], nil);
}

- (void)testContextInfoWithSubscriptedKey
{
  NSObject *object = [[NSObject alloc] init];
  object.JLT_contextInfo[@"saved"] = @"Test String";

  NSString *saved = object.JLT_contextInfo[@"saved"];
  STAssertEqualObjects(saved, @"Test String", nil);
}

#if defined(JLT_SHORTHAND)
- (void)testContextInfoShorthandWithSubscriptedKey
{
  NSObject *object = [[NSObject alloc] init];
  object.contextInfo[@"saved"] = @"Test String";

  NSString *saved = object.contextInfo[@"saved"];
  STAssertEqualObjects(saved, @"Test String", nil);
}
#endif