一般我們在xcode里面配置包含工程目錄下頭文件的時候，都要關聯着相對路徑和絕對路徑，如果只是自己用這個項目，用絕對路徑的問題不大，但是如果你把工程發給別人，別人就要在改這個絕對路徑，這時候絕對路徑的缺點立馬出現。
所以在修改User Header Search Paths這個選項的時候使用
"$(SRCROOT)/當前工程名字/需要包含頭文件所在文件夾"
將上面的雙引號里面的字符串拷貝之后，你會發現這個“$(SRCROOT)”，會自動變成當前工程所以的目錄。
這樣就可以了，發給別人，別人也不用在去修改路徑了。
xcode4的環境變量，Build Settings參數，workspace及聯編設置
一、xcode4中的環境變量
$(BUILT_PRODUCTS_DIR)
build成功后的，最終產品路徑－－可以在Build Settings參數的Per-configuration Build Products Path項里設置
$(TARGET_NAME)
目標工程名稱
$(SRCROOT)
工程文件（比如Nuno.xcodeproj）的路徑
$(CURRENT_PROJECT_VERSION)
當前工程版本號
其他：
當編譯靜態庫，設備選模擬器(iPhone 5.0 Simulator)，未設置任何Build Settings參數時，默認的基礎路徑：
/Users/xxx/Library/Developer/Xcode/DerivedData/xxxWorkspace-caepeadwrerdcrftijaolkkagbjf
下面用$()代替上面一長串東東
$(SYMROOT) = $()/Build/Products
$(BUILD_DIR) = $()/Build/Products
$(BUILD_ROOT) = $()/Build/Products
這三個變量中的$()不會隨着Build Settings參數的設置而改變
相反，以下可以通過設置而改變
$(CONFIGURATION_BUILD_DIR) = $()/Build/Products/Debug-iphonesimulator
$(BUILT_PRODUCTS_DIR) = $()/Build/Products/Debug-iphonesimulator
$(CONFIGURATION_TEMP_DIR) = $()/Build/Intermediates/UtilLib.build/Debug-iphonesimulator
$(TARGET_BUILD_DIR) = $()/Build/Products/Debug-iphonesimulator
$(SDK_NAME) = iphonesimulator5.0
$(PLATFORM_NAME) = iphonesimulator
$(CONFIGURATION) = Debug
$(TARGET_NAME) = UtilLib
$(EXECUTABLE_NAME) = libUtilLib.a 可執行文件名
${IPHONEOS_DEPLOYMENT_TARGET} 5.0
$(ACTION) = build
$(CURRENTCONFIG_SIMULATOR_DIR) 當前模擬器路徑
$(CURRENTCONFIG_DEVICE_DIR) 當前設備路徑
$(BUILD_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME =
$()/Build/Products/Debug-iphonesimulator
$(PROJECT_TEMP_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME) = $()/Build/Intermediates/UtilLib.build/Debug-iphonesimulator
自定義變量
${CONFIGURATION}-iphoneos 表示：Debug-iphoneos
${CONFIGURATION}-iphonesimulator 表示：Debug-iphonesimulator
$(CURRENTCONFIG_DEVICE_DIR) = ${SYMROOT}/${CONFIGURATION}-iphoneos
$(CURRENTCONFIG_SIMULATOR_DIR) = ${SYMROOT}/${CONFIGURATION}-iphonesimulator
自定義一個設備無關的路徑（用來存放各種架構arm6/arm7/i386輸出的產品）
$(CREATING_UNIVERSAL_DIR) = ${SYMROOT}/${CONFIGURATION}-universal
自定義變量代表的值
$(CURRENTCONFIG_DEVICE_DIR) ＝ $()/Build/Products/Debug-iphoneos
$(CURRENTCONFIG_SIMULATOR_DIR) = $()/Build/Products/Debug-iphonesimulator
$(CREATING_UNIVERSAL_DIR) = $()/Build/Products/Debug-universal
iphoneos5.0下的編譯腳本：
xcodebuild -project "UtilLib.xcodeproj" -configuration "Debug" -target "UtilLib" -sdk "iphoneos5.0" -arch "armv6 armv7" build RUN_CLANG_STATIC_ANALYZER=NO $(BUILD_DIR)="${BUILD_DIR}" BUILD_ROOT="${BUILD_ROOT}"
iphonesimulator5.0下的編譯腳本：
xcodebuild -project "UtilLib.xcodeproj" -configuration "Debug" -target "UtilLib" -sdk "iphonesimulator5.0" -arch "i386" build RUN_CLANG_STATIC_ANALYZER=NO $(BUILD_DIR)="${BUILD_DIR}" BUILD_ROOT="${BUILD_ROOT}"
加上下面一句表示輸出到文件：
> "${BUILD_ROOT}.build_output"
lipo腳本工具：合並iPhone模擬器和真機的靜態類庫，生成通用庫
lipo -create -output "${CREATING_UNIVERSAL_DIR}/${EXECUTABLE_NAME}" "${CURRENTCONFIG_DEVICE_DIR}/${EXECUTABLE_NAME}" "${CURRENTCONFIG_SIMULATOR_DIR}/${EXECUTABLE_NAME}"
意思是：把"${CURRENTCONFIG_DEVICE_DIR}目錄下的.a文件，和${CURRENTCONFIG_SIMULATOR_DIR}目錄下的.a文件合並，
在${CREATING_UNIVERSAL_DIR}目錄下，生成兩個設備都通用的靜態庫,
例如：lipo -create -output xy.a x.a y.a
二、xcode4中build Settings常見參數解析
1.Installation Directory：安裝路徑
靜態庫編譯時，在Build Settings中Installation Directory設置“$(BUILT_PRODUCTS_DIR)”
Skip Install設為YES
Installation Directory默認為/usr/local/lib
因為Build Location默認時，.a文件會放在很長（比如：/Users/xxx/Library/Developer/Xcode/DerivedData/xxxProgram
dalrvzehhtesxdfqhxixzafvddwe/Build/Products/Debug-iPhoneos）的路徑下，或是我們target指定的路徑
Skip Install如果是NO,可能會被安裝到默認路徑/usr/local/lib
2.Public Headers Folder Path：對外公開頭文件路徑
設為“include”（具體的頭文件路徑為：$(BUILT_PRODUCTS_DIR)/include/xx.h）
在最終文件.a同級目錄下生成一個include目錄
默認：/usr/local/include
Public Headers Folder Path這個路徑就是使用這lib的某工程需要依賴的外部頭文件.導入這路徑后，#include/import "xx.h"才能看到
3.User Header Search Paths：依賴的外部頭文件搜索路徑
設置為“$(BUILT_PRODUCTS_DIR)/include”
和2中路徑對應
4.Per-configuration Build Products Path：最終文件路徑
比如設為“../app”，就會在工程文件.xcodeproj上一層目錄下的app目錄里，創建最終文件
默認為$(BUILD_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)
等於$(BUILT_PRODUCTS_DIR)
5.Per-configuration Intermediate Build Files Path：臨時中間文件路徑
默認為：$(PROJECT_TEMP_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)
6.Code Signing Identity：真機調試的證書選擇
選一個和Bundle identifier相對應的證書
Library Search Paths：庫搜索路徑
Architectures：架構，設為 armv6 或 armv7
Valid Architectures：應用框架，可以設為 armv6、 armv7 或i386
Product Name:工程文件名，默認為$(TARGET_NAME)
Info.plist File：info文件路徑
Build Variants：默認為normal
Other Linker Flags：其他鏈接標簽
設為“-ObjC”
當導入的靜態庫使用了類別，需要設為-ObjC
iOS Deployment Target：ios部署對象
比如可以選擇設為，ios3到ios5的一種版本
Prefix Header：預編頭文件（比如：UtilLib/UtilLib-Prefix.pch）
Precompile Prefix Header：設為“Yes”，表示允許加入預編譯頭
三、workspace（工作區）
作用：管理多個工程（project），多工程聯編
四、workspace多工程聯編設置
一、
1.新建一個靜態庫工程，比如UtilLib，並生成UtilLib.h和UtilLib.m文件
2.選中需要公開的頭文件，
把右側欄的Target Membership中設置為public
或則，選中工程目錄target的Build Phases標簽的copy headers項，在public中添加要公開的頭文件
3.Architectures設為：armv6 armv7
4.Valid Architectures設為：armv6 armv7 i386
5.Build Products Path設為：$(SRCROOT)/../build
6.Per-configuration Build Products Path設為：
$(SRCROOT)/../build/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)
7.Per-configuration Intermediate Build Files Path設為：
$(SRCROOT)/../build/$(TARGET_NAME).build/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)
8.設置安裝路徑：Installation Directory項
9.設置對外公開的頭文件路徑：Public Headers Folder Path項
10.為靜態庫添加依賴的shell腳本
選中工程目錄target的Build Phases標簽，點擊由下角的Add Build Phase按鈕
在彈出的菜單里選擇Add run script項，然后頁面中會多出一個Run Script項
在黑框里填寫"$SRCROOT/mergeArmSymbols.sh"
建立對此腳本的依賴（編譯靜態庫的后會運行此腳本）
如果編譯時設備選的是iphone simulator：
則此腳本會在對應iphone device的產品目錄Debug-iphoneos中，生成對device有用的.a靜態庫，
相反，如果設備選的是iphone device：
則此腳本會在對應iphone simulator的產品目錄Debug-iphoneos中，生成對simulator有用的.a靜態庫
最后，此腳本調用lipo工具，把本工程生成靜態庫與此腳本生成的靜態庫合並，生成simulator和device都通用的.a文件
11.具體bash shell腳本如下：
[plain] view plaincopy
mergeArmSymbols.sh
# Version 2.0 (updated for Xcode 4, with some fixes)
# Author: Adam Martin - http://twitter.com/redglassesapps
# Based on: original script from Eonil (main changes: Eonil's script WILL NOT WORK in Xcode GUI - it WILL CRASH YOUR COMPUTER)
#
# More info: see this Stack Overflow question: http://stackoverflow.com/questions/3520977/build-fat-static-library-device-simulator-using-xcode-and-sdk-4
#################[ Tests: helps workaround any future bugs in Xcode ]########
#
DEBUG_THIS_SCRIPT="true"
if [ $DEBUG_THIS_SCRIPT = "true" ]
then
echo "########### TESTS #############"
echo "Use the following variables when debugging this script; note that they may change on recursions"
echo "BUILD_DIR = $BUILD_DIR"
echo "BUILD_ROOT = $BUILD_ROOT"
echo "CONFIGURATION_BUILD_DIR = $CONFIGURATION_BUILD_DIR"
echo "BUILT_PRODUCTS_DIR = $BUILT_PRODUCTS_DIR"
echo "CONFIGURATION_TEMP_DIR = $CONFIGURATION_TEMP_DIR"
echo "TARGET_BUILD_DIR = $TARGET_BUILD_DIR"
echo "SDK_NAME = $SDK_NAME"
echo "PLATFORM_NAME = $PLATFORM_NAME"
echo "CONFIGURATION = $CONFIGURATION"
echo "TARGET_NAME = $TARGET_NAME"
echo "ARCH_TO_BUILD = $ARCH_TO_BUILD"
echo "ARCH_TO_BUILD = $ARCH_TO_BUILD"
echo "ACTION = $ACTION"
echo "SYMROOT = $SYMROOT"
echo "EXECUTABLE_NAME = $EXECUTABLE_NAME"
echo "CURRENTCONFIG_SIMULATOR_DIR = $CURRENTCONFIG_SIMULATOR_DIR"
echo "CURRENTCONFIG_DEVICE_DIR = $CURRENTCONFIG_DEVICE_DIR"
echo "#############Other###########"
echo "BUILD_DIR/CONFIGURATION/EFFECTIVE_PLATFORM_NAME = $BUILD_DIR/$CONFIGURATION$EFFECTIVE_PLATFORM_NAME"
echo "PROJECT_TEMP_DIR/CONFIGURATION/EFFECTIVE_PLATFORM_NAME = $PROJECT_TEMP_DIR/$CONFIGURATION$EFFECTIVE_PLATFORM_NAME"
fi
#####################[ part 1 ]##################
# First, work out the BASESDK version number
# (incidental: searching for substrings in sh is a nightmare! Sob)
SDK_VERSION=$(echo ${SDK_NAME} | grep -o '.\{3\}$')
# Next, work out if we're in SIM or DEVICE
if [ ${PLATFORM_NAME} = "iphonesimulator" ]
then
OTHER_SDK_TO_BUILD=iphoneos${SDK_VERSION}
ARCH_TO_BUILD="armv6 armv7"
else
OTHER_SDK_TO_BUILD=iphonesimulator${SDK_VERSION}
ARCH_TO_BUILD="i386"
fi
echo "XCode has selected SDK: ${PLATFORM_NAME} with version: ${SDK_VERSION} (although back-targetting: ${IPHONEOS_DEPLOYMENT_TARGET})"
echo "...therefore, OTHER_SDK_TO_BUILD = ${OTHER_SDK_TO_BUILD}"
#
#####################[ end of part 1 ]##################
#####################[ part 2 ]##################
#
# IF this is the original invocation, invoke whatever other builds are required
#
# Xcode is already building ONE target... build ONLY the missing platforms/configurations.
if [ "true" == ${ALREADYINVOKED:-false} ]
then
echo "RECURSION: Not the root invocation, don't recurse"
else
# Prevent recursion
export ALREADYINVOKED="true"
echo "RECURSION: I am the root... recursing all missing build targets..."
echo "RECURSION: ...about to invoke: xcodebuild -configuration \"${CONFIGURATION}\" -target \"${TARGET_NAME}\" -sdk \"${OTHER_SDK_TO_BUILD}\" -arch \"${ARCH_TO_BUILD}\" ${ACTION} RUN_CLANG_STATIC_ANALYZER=NO"
xcodebuild -project "${TARGET_NAME}.xcodeproj" -configuration "${CONFIGURATION}" -target "${TARGET_NAME}" -sdk "${OTHER_SDK_TO_BUILD}" -arch "${ARCH_TO_BUILD}" ${ACTION} RUN_CLANG_STATIC_ANALYZER=NO BUILD_DIR="${BUILD_DIR}" BUILD_ROOT="${BUILD_ROOT}" > "${BUILD_ROOT}.build_output"
ACTION="build"
# Merge all platform binaries as a fat binary for each configurations.
# Calculate where the (multiple) built files are coming from:
CURRENTCONFIG_DEVICE_DIR=${SRCROOT}/../build/${CONFIGURATION}-iphoneos
CURRENTCONFIG_SIMULATOR_DIR=${SRCROOT}/../build/${CONFIGURATION}-iphonesimulator
echo "Taking device build from: ${CURRENTCONFIG_DEVICE_DIR}"
echo "Taking simulator build from: ${CURRENTCONFIG_SIMULATOR_DIR}"
CREATING_UNIVERSAL_DIR=${SRCROOT}/../build/${CONFIGURATION}-universal
echo "...outputing a universal arm6/arm7/i386 build to: ${CREATING_UNIVERSAL_DIR}"
# ... remove the products of previous runs of this script
# NB: this directory is only created by this script - it should be safe to delete
rm -rf "${CREATING_UNIVERSAL_DIR}"
mkdir "${CREATING_UNIVERSAL_DIR}"
#
echo "lipo: for current configuration (${CONFIGURATION}) creating output file: ${CREATING_UNIVERSAL_DIR}/${EXECUTABLE_NAME}"
lipo -create -output "${CREATING_UNIVERSAL_DIR}/${EXECUTABLE_NAME}" "${CURRENTCONFIG_DEVICE_DIR}/${EXECUTABLE_NAME}" "${CURRENTCONFIG_SIMULATOR_DIR}/${EXECUTABLE_NAME}"
#######custom########
#copy universal lib to ../libs
libsDir=../libs
includeDir=../include
rm -rf "${libsDir}"
mkdir -p "${libsDir}"
echo "cp -R ${CREATING_UNIVERSAL_DIR}/${EXECUTABLE_NAME} ${libsDir}"
cp -R "${CREATING_UNIVERSAL_DIR}/${EXECUTABLE_NAME}" "${libsDir}"
echo "cp -R ${CURRENTCONFIG_DEVICE_DIR}/include ${includeDir}"
cp -R "${CURRENTCONFIG_DEVICE_DIR}/include" "${includeDir}"
fi
下載右邊的圖片，然后把后綴改為.sh（其實就是上面的腳本，因為博客園只能上傳圖片)
靜態庫編譯后的目錄結構如下：
二、
1.新建主工程，比如Nuno，添加對靜態庫的依賴
點擊工程，在Build Phases標簽的Link Binary With Libraries項中點擊加號添加UtilLib.a庫
選中上面的紅色項，在右邊欄的Location選Relative to Project，把值設為../libs/libUtilLib.a
2.設置主工程依賴的外部頭文件路徑：User Header Search Paths項
$(SRCROOT)/../include
3.設置Header Search Paths為：$(SRCROOT)/../include
4.設置Library Search Paths為：$(SRCROOT)/../libs
編譯運行即可實現聯編
(備注：選擇模擬器iphone 5.0 simulator，編譯靜態庫的時，最終文件會在Debug-iphonesimulator，就算成功.a文件還是紅色，
這是可能是xcode的bug，不會自動切換路徑
因為$(BUILT_PRODUCTS_DIR)所指的位置，是build/Debug-iphonesos,不是包含最終.a文件的Debug-iphonesimulator；
選擇ios Device，編譯成的最終文件才在build/Debug-iphonesos下，.a文件變成非紅色
所有得用mergeArmSymbols.sh腳本來解決）
reference:
http://blog.sina.com.cn/s/blog_6de18992010190kk.html
http://www.cnblogs.com/xiaodao/archive/2012/03/28/2422091.html
