Fix the podspec which cause build issue. Update the readme

Author: dreampiggy

README.md

@@ -1,13 +1,16 @@
 # libflif + Xcode
 
 [![CI Status](http://img.shields.io/travis/SDWebImage/libflif-Xcode.svg?style=flat)](https://travis-ci.org/SDWebImage/libflif-Xcode)
+[![Version](https://img.shields.io/cocoapods/v/libflif.svg?style=flat)](http://cocoapods.org/pods/libflif)
+[![License](https://img.shields.io/cocoapods/l/libflif.svg?style=flat)](http://cocoapods.org/pods/libflif)
+[![Platform](https://img.shields.io/cocoapods/p/libflif.svg?style=flat)](http://cocoapods.org/pods/libflif)
 [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/SDWebImage/libflif-Xcode)
 
-A wrapper for [libflif](https://github.com/FLIF-hub/FLIF) + Xcode project.
+A wrapper for [libflif](https://github.com/FLIF-hub/FLIF) + Xcode project. This enables Carthage support.
 
 libflif is a codec library for [Free Lossless Image Format](https://flif.info/).
 
-This enables Carthage support.
+This repo also including the CocoaPods's spec file to use libflif with the dependency management instead of the vendored library. For CocoaPods, we use `libpng` as dependency.
 
 ## Requirements
 
@@ -18,12 +21,22 @@ This enables Carthage support.
 
 ## Installation
 
+### Carthage
+
 libflif is (via this repo) available through [Carthage](https://github.com/Carthage/Carthage).
 
 ```
 github "SDWebImage/libflif-Xcode"
 ```
 
+### CocoaPods
+
+libflif is available through [CocoaPods](https://github.com/CocoaPods/CocoaPods).
+
+```
+pod 'libflif'
+```
+
 ## Usage
 
 Use libflif as you would normally, this is just a repo that adds an Xcode proj.

libflif.podspec

@@ -36,7 +36,19 @@ FLIF is a lossless image format based on MANIAC compression.
   s.exclude_files = 'src/viewflif.c', 'src/flif.cpp'
   s.preserve_paths = 'src', 'extern'
 
+  # Try to fix that `flif-interface_common.cpp` using `#pragma once` in main file, which been included twice and cause duplicated symbols
+  s.prepare_command = <<-CMD
+                      sed -i.bak 's/flif-interface_common.cpp/flif-interface_common.hpp/g' './src/library/flif-interface_dec.cpp'
+                      sed -i.bak 's/flif-interface_common.cpp/flif-interface_common.hpp/g' './src/library/flif-interface_enc.cpp'
+                      sed -i.bak 's/flif-interface_dec.cpp/flif-interface_dec.hpp/g' './src/library/flif-interface.cpp'
+                      sed -i.bak 's/flif-interface_enc.cpp/flif-interface_enc.hpp/g' './src/library/flif-interface.cpp'
+                      mv './src/library/flif-interface_common.cpp' './src/library/flif-interface_common.hpp'
+                      mv './src/library/flif-interface_dec.cpp' './src/library/flif-interface_dec.hpp'
+                      mv './src/library/flif-interface_enc.cpp' './src/library/flif-interface_enc.hpp'
+                      CMD
+
   s.xcconfig = {
+    'HEADER_SEARCH_PATHS' => '$(inherited) ${PODS_ROOT}/libpng',
     'OTHER_CPLUSPLUSFLAGS' => '$(inherited) -ftree-vectorize',
     'GCC_PREPROCESSOR_DEFINITIONS' => '$(inherited) LODEPNG_NO_COMPILE_DISK'
   }