升级Xcode7发现的一些问题和解决方案

1、按开发的需要，升级了xcode版本，真机编译项目的时候发现提示错误信息：

(null): URGENT: all bitcode will be dropped because ‘xxxx’ was built without bitcode. You must rebuild it with bitcode enabled (Xcode setting ENABLE_BITCODE), obtain an updated library from the vendor, or disable bitcode for this target. Note: This will be an error in the future.

因为我用了的是激光推送sdk,且问题指向确实属于是该sdk的静态库。结果发现激光官网并没有跟新新的版本兼容ios9，后来网上给出了另一个解决方案：

2、做网络请求的时候发生提示

  The resource could not be loaded because the App Transport Security policy requires the  use of  a secure  connection 

Google后查证，iOS9引入了新特性App Transport Security (ATS)。详情：App Transport Security (ATS)

新特性要求App内访问的网络必须使用HTTPS协议。
但是现在公司的项目使用的是HTTP协议，使用私有加密方式保证数据安全。现在也不能马上改成HTTPS协议传输。
最终找到以下解决办法：
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。

3、还有一个比较特别的错误：

Undefined symbols for architecture x86_64:
  "_u_errorName", referenced from:
      _rkl_NSExceptionForRegex in MOBFoundation
      _rkl_userInfoDictionary in MOBFoundation
      _cm_rkl_NSExceptionForRegex in AGCommon
      _cm_rkl_userInfoDictionary in AGCommon
  "_u_strlen", referenced from:
      _rkl_userInfoDictionary in MOBFoundation
      _cm_rkl_userInfoDictionary in AGCommon
  "_uregex_appendReplacement", referenced from:
      _rkl_replaceAll in MOBFoundation
      _cm_rkl_replaceAll in AGCommon
  "_uregex_appendTail", referenced from:
      _rkl_replaceAll in MOBFoundation
      _cm_rkl_replaceAll in AGCommon
  "_uregex_clone", referenced from:
      -[MOBFRKLBlockEnumerationHelper initWithRegex:options:string:range:error:] in MOBFoundation
      -[CMRKLBlockEnumerationHelper initWithRegex:options:string:range:error:] in AGCommon
  "_uregex_close", referenced from:
      _rkl_clearCachedRegex in MOBFoundation
      _cm_rkl_clearCachedRegex in AGCommon
  "_uregex_end", referenced from:
      _rkl_performRegexOp in MOBFoundation
      _rkl_findRanges in MOBFoundation
      _rkl_search in MOBFoundation
      _cm_rkl_performRegexOp in AGCommon
      _cm_rkl_findRanges in AGCommon
      _cm_rkl_search in AGCommon
  "_uregex_find", referenced from:
      _rkl_search in MOBFoundation
      _cm_rkl_search in AGCommon
  "_uregex_findNext", referenced from:
      _rkl_search in MOBFoundation
      _rkl_replaceAll in MOBFoundation
      _cm_rkl_search in AGCommon
      _cm_rkl_replaceAll in AGCommon
  "_uregex_groupCount", referenced from:
      _rkl_getCachedRegex in MOBFoundation
      _cm_rkl_getCachedRegex in AGCommon
  "_uregex_open", referenced from:
      _rkl_getCachedRegex in MOBFoundation
      _cm_rkl_getCachedRegex in AGCommon
  "_uregex_reset", referenced from:
      _rkl_replaceAll in MOBFoundation
      _cm_rkl_replaceAll in AGCommon
  "_uregex_setText", referenced from:
      -[MOBFRKLBlockEnumerationHelper initWithRegex:options:string:range:error:] in MOBFoundation
      _rkl_performRegexOp in MOBFoundation
      _rkl_clearCachedRegexSetTo in MOBFoundation
      -[CMRKLBlockEnumerationHelper initWithRegex:options:string:range:error:] in AGCommon
      _cm_rkl_performRegexOp in AGCommon
      _cm_rkl_clearCachedRegexSetTo in AGCommon
  "_uregex_start", referenced from:
      _rkl_performRegexOp in MOBFoundation
      _rkl_findRanges in MOBFoundation
      _rkl_search in MOBFoundation
      _cm_rkl_performRegexOp in AGCommon
      _cm_rkl_findRanges in AGCommon
      _cm_rkl_search in AGCommon
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

解决方案是：

4. 十月十六日 发现了一些新问题，

<Error>: CGContextSaveGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
<Error>: CGContextTranslateCTM: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
<Error>: CGContextRestoreGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.

出错原因：设置app的状态栏样式的使用使用了旧的方式，在info.plist里面设置了View controller-based status bar appearance为NO，默认为YES，一般式iOS6的时候使用这种方式，iOS7，8也兼容，但是到了iOS9就报了警告。

解决办法：

删除 原先的设置代码

        /*
// ================
// 设置可修改状态栏色彩 首先要在plist 中添加key View controller-based status bar appearance 设置NO
// ================
// */
// [[UIApplication sharedApplication ] setStatusBarStyle:UIStatusBarStyleLightContent];

修改方式将View controller-based status bar appearance设置为YES，然后使用新的方式来实现状态栏的样式。
然后再AppDelegate.m 添加方法

-(UIStatusBarStyle)preferredStatusBarStyle {
    return UIStatusBarStyleLightContent;
}

5.ios9 必须在 didFinishLaunchingWithOptions 结束之前设置rootViewController,否则会崩溃
6.Xcode7 感觉修改了东西 记得一定要先clean下，这个感觉坑比较大。有时候忘记了，一直纠结怎么效果没变。