26 The Xcode Build System 389
Xcode Build Variables....................................................................392
Settings Hierarchy ........................................................................393
Editing Build Variables...........................................................395
Configurations.............................................................................396
Adjusting Configurations .......................................................396
Adding Configurations ..........................................................398
Configuration Files .......................................................................398
Creating a Configuration File..................................................398
SDK- and Architecture-Specific Settings ....................................399
Preprocessing xcconfig Files...................................................399
The xcodebuild Tool .....................................................................400
Custom Build Rules ......................................................................401
The Build Log ..............................................................................403
A Simple Build Transcript...............................................................404
Resources ............................................................................406
Precompiled Header ..............................................................407
Compiling Source Files ..........................................................408
Linking ...............................................................................409
Making a Universal Binary .....................................................410
Touch .................................................................................410
Summary ....................................................................................410
27 Instruments 411
What Instruments Is .....................................................................411
Running Instruments ....................................................................412
The Trace Document Window.................................................413
The Library..........................................................................419
Instrument Configuration ......................................................420
Recording............................................................................421
Saving and Reopening ...........................................................423
The Instruments...........................................................................424
Core Data............................................................................424
Custom Instruments .............................................................425
Dispatch .............................................................................425
File System ..........................................................................425
Garbage Collection ...............................................................426
Graphics .............................................................................426
Input/Output .......................................................................426
Master Tracks .......................................................................426
Memory ..............................................................................426
System ................................................................................427
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