初识IOS

编译环境： ssh cloud@10.0.4.148  mx-cloud

1、关于ARM架构

　　IPHONE上的ARM-CPU架构在不断的进化过程中，目前情况如下：

ARMv8 / ARM64 = iPhone 5s
ARMv7s = iPhone 5, iPhone 5c, iPad 4
ARMv7  = iPhone 3GS, iPhone 4, iPhone 4S, iPod 3G/4G/5G, iPad, iPad 2, iPad 3, iPad Mini  
ARMv6  = iPhone 2G/3G, iPod 1G/2G

2、关于XCode版本问题

　　1）先查看xcode位置：xcode-select --print-path

　　2）然后在xcode的目录下面运行：/Developer/usr/bin/xcodebuild -version

3、关于IOS中的交叉编译

　　http://hi.baidu.com/yetao19860606/item/aa1eda0cc3b06276bee97e6c

　　通过 --host 来指定，同时需要使用 -isysroot 来指定目标设备SDK的类库于头文件

http://stackoverflow.com/questions/7850624/how-to-compile-fftw3-on-ios

--build=BUILD     configure for building on BUILD [guessed]
--host=HOST       cross-compile to build programs to run on HOST [BUILD]
So the key is to pass --host=arm-apple-darwin10, and execute configure with the correct alterations to PATH, CFLAGS, LDFLAGS, etc.

PATH=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:$PATH \
../configure --host=arm-apple-darwin10 CFLAGS="-I/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk/usr/include -I/Library/iPhone/include -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk" \
CC=arm-apple-darwin10-gcc-4.2.1 \
CPP=cpp \
LDFLAGS="-isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk" \
--enable-single