From 0a5150ef375d68157be991e4363b39c95355ecda Mon Sep 17 00:00:00 2001
From: R0CKSTAR <yeahdongcn@gmail.com>
Date: Wed, 28 Sep 2016 09:54:24 +0800
Subject: [PATCH] Add String extension to convert argb string to rgba string

---
 HEXColor/UIColorExtension.swift   | 27 ++++++++++++++++++++++++++-
 HEXColorTests/HEXColorTests.swift | 10 ++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/HEXColor/UIColorExtension.swift b/HEXColor/UIColorExtension.swift
index f674678..bf06bc6 100644
--- a/HEXColor/UIColorExtension.swift
+++ b/HEXColor/UIColorExtension.swift
@@ -91,7 +91,7 @@ extension UIColor {
         var hexValue:  UInt32 = 0
         
         guard Scanner(string: hexString).scanHexInt32(&hexValue) else {
-                throw UIColorInputError.unableToScanHexValue
+            throw UIColorInputError.unableToScanHexValue
         }
         
         switch (hexString.characters.count) {
@@ -140,3 +140,28 @@ extension UIColor {
         }
     }
 }
+
+extension String {
+    /**
+     Convert argb string to rgba string.
+     */
+    public func argb2rgba() -> String? {
+        guard self.hasPrefix("#") else {
+            return nil
+        }
+        
+        let hexString: String = self.substring(from: self.characters.index(self.startIndex, offsetBy: 1))
+        switch (hexString.characters.count) {
+        case 4:
+            return "#"
+                + hexString.substring(from: self.characters.index(self.startIndex, offsetBy: 1))
+                + hexString.substring(to: self.characters.index(self.startIndex, offsetBy: 1))
+        case 8:
+            return "#"
+                + hexString.substring(from: self.characters.index(self.startIndex, offsetBy: 2))
+                + hexString.substring(to: self.characters.index(self.startIndex, offsetBy: 2))
+        default:
+            return nil
+        }
+    }
+}
diff --git a/HEXColorTests/HEXColorTests.swift b/HEXColorTests/HEXColorTests.swift
index 897da59..843ec75 100644
--- a/HEXColorTests/HEXColorTests.swift
+++ b/HEXColorTests/HEXColorTests.swift
@@ -292,6 +292,16 @@ class HEXColorTests: XCTestCase {
         XCTAssertEqual("#AABBCC", hexColor.hexString(false))
         XCTAssertEqual("#AABBCCDD", hexColor.hexString(true))
     }
+    
+    // MARK: - Convert argb string to rgba string
+    
+    func testArgb2rgba() {
+        let rgba = "#2468".argb2rgba()
+        XCTAssertEqual("#4682", rgba)
+        
+        let rrggbbaa = "#22446688".argb2rgba()
+        XCTAssertEqual("#44668822", rrggbbaa)
+    }
 }
 
 extension UIColor {