AFNetworking 使用中报错

好久没用 http相关的库，今天使用， 选用AFNetworking,github下载，引入工程，记录下中间使用中遇到的问题

1.在非ARC工程中使用ARC的文件，在project->Build Phases->Compile Sources 文件编辑参数 -fobjc-arc

　PS:在ARC项目中使用非ARC文件：文件编辑参数 -fnoobjc-arc

2.编译时报错，

Undefined symbols for architecture i386:
"_UTTypeCopyPreferredTagWithClass", referenced from:
_AFContentTypeForPathExtension in AFURLRequestSerialization.o
"_UTTypeCreatePreferredIdentifierForTag", referenced from:
_AFContentTypeForPathExtension in AFURLRequestSerialization.o
"_kUTTagClassFilenameExtension", referenced from:
_AFContentTypeForPathExtension in AFURLRequestSerialization.o
"_kUTTagClassMIMEType", referenced from:
_AFContentTypeForPathExtension in AFURLRequestSerialization.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

解决 project->Build Phases-> Link Binary With Libraries 添加[/code]

MobileCoreServices.framework
SystemConfiguration.framework

3. 请求url 出现错误：The resource could not be loaded because the App Transport Security policy requires the use of a secure connection. 
原因iOS9引入了新特性[code]App Transport Security (ATS)，

要求App内访问的网络必须使用

HTTPS

协议。[/code]
　　解决方案： 1.在Info.plist中添加

NSAppTransportSecurity

类型

Dictionary

。

　　　　　　　2.在

NSAppTransportSecurity

下添加

NSAllowsArbitraryLoads

类型

Boolean

,值设为

YES

4.编译出现   AF_Require_noErr(SecItemExport(key, kSecFormatUnknown, kSecItemPemArmour, NULL, &data), _out);  出现kSecFormatUnknown无法识别  如果是2.6版本，请换2.5 就没问题了