ios应用程序在运行时在哪里找到与它链接的Apple提供的dylib？

Question

I'm trying to make some light in my head about what happens with applications running on iOS. I can see down under /Developer/Platforms/iPhoneOS.platform there are several dylibs that are probably linked against upon using certain Frameworks? In any case, my question is general: if for whatever reason an iOS app comes to be built with a dependency on an official (ie Apple provided) dylib, what will happen at runtime when running on an iDevice?

1. The dylib is bundled together with the application
2. The dylib is already on the device and the runtime linker will resolve the dependencies using what it finds on the device.

I think 2) is what should happen, but I'm unsure and couldn't find any places that clearly states that.

Answer 1

Yes your right it's 2) the libraries are dynamically linked. You can investigate using otool , for example:

$ cd /path/to/App.app
$ lipo -info appbinary 
Non-fat file: appbinary is architecture: armv7
$ otool -L appbinary 
appbinary:
    /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation (compatibility version 150.0.0, current version 675.0.0)
    /System/Library/Frameworks/Foundation.framework/Foundation (compatibility version 300.0.0, current version 881.0.0)
    /System/Library/Frameworks/UIKit.framework/UIKit (compatibility version 1.0.0, current version 1600.0.0)
    /System/Library/Frameworks/CoreGraphics.framework/CoreGraphics (compatibility version 64.0.0, current version 600.0.0)
    /System/Library/Frameworks/QuartzCore.framework/QuartzCore (compatibility version 1.2.0, current version 1.7.0)
    /System/Library/Frameworks/OpenGLES.framework/OpenGLES (compatibility version 1.0.0, current version 1.0.0)
    /System/Library/Frameworks/OpenAL.framework/OpenAL (compatibility version 1.0.0, current version 1.0.0)
    /System/Library/Frameworks/SystemConfiguration.framework/SystemConfiguration (compatibility version 1.0.0, current version 432.0.0)
    /System/Library/Frameworks/CFNetwork.framework/CFNetwork (compatibility version 1.0.0, current version 548.0.3)
    /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 53.4.0)
    /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.5)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 161.1.0)
    /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 6.0.0)
    /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)