UIView+Motif.h

#import <UIKit/UIKit.h>
#import <Motif/Motif.h>

NS_ASSUME_NONNULL_BEGIN

/**
 *  Extension that allows defining a global theme applier, which will be used 
 *  when a class is set via Storyboard/XIB and a theme name is ommited.
 */
@interface UIView (MotifDefaultTheme)

/**
 *  Sets the default theme applier.
 *
 *  @param themeApplier the theme applier to be set, or nil to unset the current applier.
 */
+ (void)setDefaultMotifThemeApplier:(nullable id<MTFThemeApplier>)themeApplier;

/**
 *  Creates a theme applier from the theme name and sets it as default.
 *
 *  @param themeFile the theme name to be used by the new default applier, or nil 
 *          to unset the current applier.
 */
+ (void)setDefaultMotifThemeApplierWithFileNamed:(nullable NSString *)themeFile;

/**
 *  Creates a theme applier from an array of theme names and sets it as default.
 *
 *  @param themeFiles the theme names to be used by the new default applier, or nil 
 *          to unset the current applier.
 */
+ (void)setDefaultMotifThemeApplierWithFilesNamed:(nullable NSArray<NSString *> *)themeFiles;

/**
 *  The current default theme applier.
 *
 *  @return current default theme applier, or nil if not set.
 */
+ (nullable id<MTFThemeApplier>)defaultMotifThemeApplier;

@end

/**
 *  Extension that allows setting a Motif theme name and Class for any UIView in a 
 *  Storyboard or XIB file. If the theme name is ommited, the default theme applier 
 *  will be used if set.
 */
@interface UIView (MotifStoryboard)

/**
 *  The theme name to be used. You should prefer to use a default theme applier instead, 
 *  since setting this causes a new theme applier to be created every time the class is changed.
 */
@property (nonatomic, strong, nullable) IBInspectable NSString *motifTheme;

/**
 *  The class to be used by this element.
 */
@property (nonatomic, strong, nullable) IBInspectable NSString *motifClass;

@end

NS_ASSUME_NONNULL_END

UIView+Motif.m

#import "UIView+Motif.h"

#import <objc/runtime.h>

@implementation UIView (MotifDefaultTheme)

+ (void)setDefaultMotifThemeApplier:(id<MTFThemeApplier>)themeApplier {
    objc_setAssociatedObject(self, @selector(defaultMotifThemeApplier), themeApplier, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

+ (void)setDefaultMotifThemeApplierWithFileNamed:(NSString *)themeFile {
    [self setDefaultMotifThemeApplierWithFilesNamed:(themeFile != nil ? @[themeFile] : nil)];
}

+ (void)setDefaultMotifThemeApplierWithFilesNamed:(NSArray<NSString *> *)themeFiles
{
    id<MTFThemeApplier> themeApplier = nil;
    
    if (themeFiles != nil) {
        NSError *error = nil;
        themeApplier = [MTFTheme themeFromFilesNamed:themeFiles
                                               error:&error];
        
        if (error != nil) {
            NSLog(@"<Motif/Error> Error creating theme applier: %@", error);
        }
    }
    
    [self setDefaultMotifThemeApplier:themeApplier];
}

+ (id<MTFThemeApplier>)defaultMotifThemeApplier {
    return objc_getAssociatedObject(self, @selector(defaultMotifThemeApplier));
}

@end

@implementation UIView (MotifStoryboard)

@dynamic motifTheme;
@dynamic motifClass;

- (NSString *)motifTheme {
    return objc_getAssociatedObject(self, @selector(motifTheme));
}

- (void)setMotifTheme:(NSString *)motifTheme {
    objc_setAssociatedObject(self, @selector(motifTheme), motifTheme, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSString *)motifClass {
    return objc_getAssociatedObject(self, @selector(motifClass));
}

- (void)setMotifClass:(NSString *)motifClass {
    objc_setAssociatedObject(self, @selector(motifClass), motifClass, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    
    if (motifClass == nil) {
        return;
    }
    
    id<MTFThemeApplier> themeApplier = [UIView defaultMotifThemeApplier];
    
    if (self.motifTheme != nil) {
        NSError *error = nil;
        themeApplier = [MTFTheme themeFromFileNamed:self.motifTheme
                                              error:&error];
        
        if (error != nil) {
            NSLog(@"<Motif/Error> Error creating theme applier: %@", error);
        }
    }
    
    if (themeApplier != nil) {
        NSError *error = nil;
        [themeApplier applyClassWithName:self.motifClass
                                      to:self
                                   error:&error];
        
        if (error != nil) {
            NSLog(@"<Motif/Error> Error applying class: %@", error);
        }
    } else {
        NSLog(@"<Motif/Error> No theme to use for class '%@' in %@. Either set a value for Motif Theme, or set the default theme applier in UIView", motifClass, self);
    }
}

@end