Do not let Xcode compressed APNG files.

Demo/YYWebImageDemo.xcodeproj/project.pbxproj

@@ -574,12 +574,14 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				COMPRESS_PNG_FILES = NO;
 				FRAMEWORK_SEARCH_PATHS = "\"$(SRCROOT)/../Vendor\"";
 				INFOPLIST_FILE = YYWebImageDemo/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.ibireme.YYWebImageDemo;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				STRIP_PNG_TEXT = NO;
 			};
 			name = Debug;
 		};
@@ -587,12 +589,14 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				COMPRESS_PNG_FILES = NO;
 				FRAMEWORK_SEARCH_PATHS = "\"$(SRCROOT)/../Vendor\"";
 				INFOPLIST_FILE = YYWebImageDemo/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.ibireme.YYWebImageDemo;
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				STRIP_PNG_TEXT = NO;
 			};
 			name = Release;
 		};