Support keyed images

Currently you can override image "foo" (foo.png) in Bundle A with
foo.png in Bundle B.

However, sometimes you need to override image "foo" (foo.png) in Bundle
A with quack.png in Bundle B. Basically you want to request imageNamed:
"Foo", but have the theme swap that out for "Quack" via the plist, and
then try to find imageNamed: "Quack" instead.

Author: jrapoport

AWLThemeManager/AWLThemeManager.h

@@ -25,6 +25,10 @@
 - (UIFont*)fontForKey:(NSString*)key;
 - (UIFont *)fontForKey:(NSString *)key forTheme:(NSString*)themeName;
 
+//Get img name from defaults.plist, and then img from theme bundle
+- (UIImage *)imageforKey:(NSString *)key;
+- (UIImage *)imageforKey:(NSString *)key forTheme:(NSString*)themeName;
+
 //Get img from theme bundle
 - (UIImage*)imageNamed:(NSString*)imgName;
 - (UIImage *)imageNamed:(NSString *)imgName forTheme:(NSString*)themeName;

AWLThemeManager/AWLThemeManager.m

@@ -118,6 +118,22 @@ - (UIColor*)colorFromString:(NSString*)colorValue
     return nil;
 }
 
+- (UIImage *)imageforKey:(NSString *)key
+{
+    return [self imageforKey:key forTheme:self.currentTheme];;
+}
+
+- (UIImage *)imageforKey:(NSString *)key forTheme:(NSString*)themeName
+{
+    if ([self isValidString:themeName] == NO || [self isValidString:key] == NO) {
+        return nil;
+    }
+    
+    NSString *imageName = [self objectForKey:key forTheme:themeName];
+    
+    return [self imageNamed:imageName forTheme:themeName];
+}
+
 - (UIImage *)imageNamed:(NSString *)imgName
 {
     return [self imageNamed:imgName forTheme:self.currentTheme];;