Override appearance proxy for a certain UIViewController

OK, the case is that in your application take advantage of the appearance proxy (iOS 5) for presenting a custom UI for your app.

In AppDelegate.m you have

- (void)customizeAppearance
{
...

// UISegmentedControl
UIImage *segmentSelected = [[UIImage imageNamed:@"segcontrol_sel"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 16, 0, 16)];
UIImage *segmentUnselected = [[UIImage imageNamed:@"segcontrol_uns"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 16, 0, 16)];
UIImage *segmentSelectedUnselected = [UIImage imageNamed:@"segcontrol_divider"];
UIImage *segUnselectedSelected = [UIImage imageNamed:@"segcontrol_divider"];
UIImage *segUnselectedUnselected = [UIImage imageNamed:@"segcontrol_divider"];

[[UISegmentedControl appearance] setBackgroundImage:segmentUnselected forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setBackgroundImage:segmentSelected forState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segmentSelectedUnselected forLeftSegmentState:UIControlStateSelected
rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segUnselectedSelected forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segUnselectedUnselected forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];

}

and everything is working fine until???

Until the moment that you decide that in a UiSegmentedControl in a specific UIViewController you want a different appearance.

This is the time that you want to override the universal appearance proxy behaviour and make an exception.

In order to achieve this you can use

+ (id)appearanceWhenContainedIn:(Class <UIAppearanceContainer>)ContainerClass, … NS_REQUIRES_NIL_TERMINATION;

method like:

- (void)customizeAppearance
{
   ...
// UISegmentedControl

UIImage *segmentSelected = [[UIImage imageNamed:@"segcontrol_sel"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 16, 0, 16)];
UIImage *segmentSelectedBig = [[UIImage imageNamed:@"segcontrol_sel_big"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 16, 10, 16)];

UIImage *segmentUnselected = [[UIImage imageNamed:@"segcontrol_uns"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 16, 0, 16)];
UIImage *segmentUnselectedBig = [[UIImage imageNamed:@"segcontrol_uns_big"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 16, 10, 16)];

UIImage *segmentSelectedUnselected = [UIImage imageNamed:@"segcontrol_divider"];
UIImage *segmentSelectedUnselectedBig = [UIImage imageNamed:@"segcontrol_divider_big"];

UIImage *segUnselectedSelected = [UIImage imageNamed:@"segcontrol_divider"];
UIImage *segUnselectedSelectedBig = [UIImage imageNamed:@"segcontrol_divider_big"];

UIImage *segUnselectedUnselected = [UIImage imageNamed:@"segcontrol_divider"];

[[UISegmentedControl appearance] setBackgroundImage:segmentUnselected forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setBackgroundImage:segmentSelected forState:UIControlStateSelected barMetrics:UIBarMetricsDefault];

[[UISegmentedControl appearance] setDividerImage:segmentSelectedUnselected forLeftSegmentState:UIControlStateSelected
                                   rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segUnselectedSelected forLeftSegmentState:UIControlStateNormal
                                   rightSegmentState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setDividerImage:segUnselectedUnselected forLeftSegmentState:UIControlStateNormal
                                   rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UISegmentedControl appearance] setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor colorWithRed:220.0/255.0 green:255.0/255.0 blue:255.0/255.0 alpha:1.0], UITextAttributeTextColor, [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:1.0], UITextAttributeTextShadowColor, [NSValue valueWithUIOffset:UIOffsetMake(0, -1)], UITextAttributeTextShadowOffset, [UIFont fontWithName:@"Avenir-Medium" size:0.0], UITextAttributeFont, nil] forState:UIControlStateNormal];

// override appearance proxy for PetDetailsViewController
id bigSegmentedControlAppearance = [UISegmentedControl appearanceWhenContainedIn:[PetDetailsViewController class], nil];

[bigSegmentedControlAppearance setBackgroundImage:segmentSelectedBig forState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
[bigSegmentedControlAppearance setBackgroundImage:segmentUnselectedBig forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[bigSegmentedControlAppearance setDividerImage:segmentSelectedUnselectedBig forLeftSegmentState:UIControlStateSelected
                                 rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[bigSegmentedControlAppearance setDividerImage:segUnselectedSelectedBig forLeftSegmentState:UIControlStateNormal
                                 rightSegmentState:UIControlStateSelected barMetrics:UIBarMetricsDefault];

}

At the beginning we define two versions for each image and then using appearanceWhenContainedIn method we define the appearence for of UISegmentedControl only for the specific UIViewController.

Credits to Mr.Dave DeLong