iOS - Xcode升级到5.1& iOS升级到iOS7.1问题：

http://blog.csdn.net/ifziv/article/details/21079065

一：

iOS7.1时XCode为5.0.2 无法真机调试.升级XCode到5.1.

二：

Xcode升级到5.1了，Apple默认让所有App都通过64位编译器编译。通过下面的3步可以关闭： 

1.选中Targets—>Build Settings—>Architectures。

2.双击Architectures，选择other，删除$(ARCH_STANDARD)，然后增加armv7和armv7s。

3.clean一下再编译。

三：

Xcode 5.1， iOS SDK 7.1 后，TableView Cell clipsToBounds 属性默认都是NO，导致以前用的把cell的height设为0来隐藏某个cell的方法没用了,cell内容会叠起来。

 解决方法就是手动把clipsToBounds改YES，或者Storyboard里Clip Subview打勾。

UILabel 的 clipsToBounds 属性也被默认设置为NO，如果想隐藏超出的部分也需要手动设置为  *.clipsToBounds = YES;

四 ：

XCODE5.0升到XCODE5.1后LLVM也从5.0升到5.1，工程报下面的错误了:

clang: error: unknown argument: '-fno-obj-arc' [-Wunused-command-line-argument-hard-error-in-future] clang: note: this will be a hard error (cannot be downgraded to a warning) in the future Command /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
failed with exit code 1

从Xcode Release Notes找到说明

The Apple LLVM compiler in Xcode 5.1 treats unrecognized command-line options as errors. This issue has been seen when building both Python native extensions and Ruby Gems, where some invalid compiler options are currently specified. Projects usinginvalid compiler
options will need to be changed to remove those options. To help ease that transition, the compiler will temporarily accept an option to downgrade the error to a warning:

将Compile sources中'-fno-obj-arc'改成'-fno-objc-arc'