support rgba color definitions

Demo/DB5Demo/DB5.plist

@@ -7,7 +7,7 @@
 		<key>backgroundColor</key>
 		<string>708090</string>
 		<key>labelTextColor</key>
-		<string>ececec</string>
+		<string>rgba(236, 236, 236, 1.0)</string>
 		<key>labelFont</key>
 		<string>Avenir-Medium</string>
 		<key>labelFontSize</key>

Source/VSTheme.h

@@ -30,7 +30,7 @@ typedef NS_ENUM(NSUInteger, VSTextCaseTransform) {
 - (NSInteger)integerForKey:(NSString *)key;
 - (CGFloat)floatForKey:(NSString *)key;
 - (UIImage *)imageForKey:(NSString *)key; /*Via UIImage imageNamed:*/
-- (UIColor *)colorForKey:(NSString *)key; /*123ABC or #123ABC: 6 digits, leading # allowed but not required*/
+- (UIColor *)colorForKey:(NSString *)key; /*6 hexadecimal characters values: #123ABC, leading # not required OR rgba with interger values: rgba(18, 58, 188, 0.8), whitespace between values ignored*/
 - (UIEdgeInsets)edgeInsetsForKey:(NSString *)key; /*xTop, xLeft, xRight, xBottom keys*/
 - (UIFont *)fontForKey:(NSString *)key; /*x and xSize keys*/
 - (CGPoint)pointForKey:(NSString *)key; /*xX and xY keys*/

Source/VSTheme.m

@@ -11,6 +11,7 @@
 
 static BOOL stringIsEmpty(NSString *s);
 static UIColor *colorWithHexString(NSString *hexString);
+static UIColor *colorWithRGBAString(NSString *rgbaString);
 
 
 @interface VSTheme ()
@@ -117,7 +118,7 @@ - (UIColor *)colorForKey:(NSString *)key {
 		return cachedColor;
 
 	NSString *colorString = [self stringForKey:key];
-	UIColor *color = colorWithHexString(colorString);
+	UIColor *color = [colorString hasPrefix:@"rgba"] ? colorWithRGBAString(colorString) : colorWithHexString(colorString);
 	if (color == nil)
 		color = [UIColor blackColor];
 
@@ -284,3 +285,25 @@ static BOOL stringIsEmpty(NSString *s) {
 
 	return [UIColor colorWithRed:(CGFloat)red/255.0f green:(CGFloat)green/255.0f blue:(CGFloat)blue/255.0f alpha:1.0f];
 }
+
+static UIColor *colorWithRGBAString(NSString *rgbaString) {
+    static NSString* const kDB5RGBAStringPattern = @"^rgba\\(\\s*(\\d{1,3})\\s*,\\s*(\\d{1,3})\\s*,\\s*(\\d{1,3})\\s*,\\s*(\\d{1}\\.\\d+)\\s*\\)$";
+    static NSRegularExpression *rgbaRegularExpression;
+    if (!rgbaRegularExpression) {
+        rgbaRegularExpression = [NSRegularExpression regularExpressionWithPattern:kDB5RGBAStringPattern options:NSRegularExpressionCaseInsensitive error:nil];
+    }
+
+    NSArray* matches = [rgbaRegularExpression matchesInString:rgbaString options:0 range:NSMakeRange(0, [rgbaString length])];
+    if ([matches count] != 1) {
+        return nil;
+    }
+    NSTextCheckingResult *result = [matches firstObject];
+    if (result.numberOfRanges != 5) {
+        return nil;
+    }
+    int red = [[rgbaString substringWithRange:[result rangeAtIndex:1]] intValue];
+    int green = [[rgbaString substringWithRange:[result rangeAtIndex:2]] intValue];
+    int blue = [[rgbaString substringWithRange:[result rangeAtIndex:3]] intValue];
+    CGFloat alpha = [[rgbaString substringWithRange:[result rangeAtIndex:4]] floatValue];
+    return [UIColor colorWithRed:(CGFloat)red/255.0f green:(CGFloat)green/255.0f blue:(CGFloat)blue/255.0f alpha:alpha];
+}