External make files can be used with Xcode, using an External Build System project template. These files can be modified to take advantage of Xcode project settings, such as the build type and location, while still useful when used separately.
Create an External Project
To create a new external build project, in Xcode select the New->New Project... dialog, then select the External Build System template. Put the project in the same directory as the target Makefile.
Add Xcode Build Settings
When invoking an external build, Xcode defines environment variables for its build settings. These settings define where build files are created, as well as compiler and linker flags. We use Make's conditional directives to modify the build when it is invoked by Xcode.
Here's an example, where the variables being set (such as BUILD_DIR) can be whatever name you want, while the conditionals use the environment variables Xcode set:
ifdef CONFIGURATION_BUILD_DIR
# In Xcode build
BUILD_DIR = $(CONFIGURATION_BUILD_DIR)/build
ARCHFLAGS = $(ARCHS:%=-arch %)
SDKFLAGS = -isysroot $(SDKROOT)
else
# In command-line build
BUILD_DIR = $(HOME)/build
ARCHFLAGS =
SDKFLAGS =
endif
ifdef OPTIMIZATION_LEVEL
DEBUGFLAGS := $(DEBUGFLAGS) -O$(OPTIMIZATION_LEVEL)
endif
ifdef OTHER_CFLAGS
DEBUGFLAGS := $(DEBUGFLAGS) $(OTHER_CFLAGS)
endif
# Workaround for iPhoneSimulator SDK's gcc bug
ifdef EFFECTIVE_PLATFORM_NAME
ifneq ($(EFFECTIVE_PLATFORM_NAME), -iphonesimulator)
WARNINGS := $(WARNINGS) -Wreturn-type
endif
endif
J2OBJCC_FLAGS = $(WARNINGS) $(SDKFLAGS) $(ARCHFLAGS) $(DEBUGFLAGS)
J2OBJCC = $(J2OBJC_DIST)/j2objcc $(J2OBJCC_FLAGS)