iOS cross-compiling dylib

iOS cross-compiling dylib

Due to multiple static libraries, LIBES,LIBFFMPEG,LIBMT. Libpcap not easy to use

In encapsulating a layer of interfaces, a dynamic library (c code) is generated, called by the upper iOS app.

Attention:

ARCH designation, can specify multiple, backwards compatible!

The default instruction set for Apple mobile devices so far-------------------------------------------------------------------------------------  ARMV6 devices: IPhone, IPhone2, iphone3g, first generation, second generation IPod TOUCHARMV7 devices: iphone3gs, iPhone4, iphone4s                      iPad, IPad2, IPad3 (The N ew ipad), ipad mini                      ipod Touch 3G, ipod touch4armv7s device: IPhone5, IPHONE5C, IPad4 (ipad with Retina Display) arm64 device: IP hone5s, ipad Air, ipad mini2 (ipad mini with Retina Display)

To view dynamic library information using the Lipo-info command

Input file Libmtsql.a is not a FAT file

Non-fat FILE:LIBMTSQL.A is architecture:armv7

You can also use Readelf to read header information.

NM command to view symbolic information, here are some common symbol types

NM output character	Meaning
R	Read only symbol. For example, there is a const MAXDATA = 3095 in the code; Then Maxdata is a read only symbol
N	This is a debug symbol
D	This is a symbol of a variable that has already been initialized. For example, in code int i = 1 and char *str = "Hello" then I and STR are all symbols of this type
T	The symbol for the text segment. Subroutines are such symbols, such as the implementation of a function in a file, then function is the symbol
U	Undefined symbol. If a nonexistent function is referenced in the file, then these undefined function symbols are of this type
S	An uninitialized symbol, such as a global variable int s; the symbol for S is this type

When more than one arch structure is specified, multiple addresses appear for the same symbol! Meet today: ios_base_sdk= "8.1" ios_deploy_tgt= "7.1" devroot = "$ (shell xcode-select-p)/platforms/iphoneos.platform/developer" sdkroot = "$ (devroot)/sdks/iphoneos$ (IOS_BASE_SDK). SDK"

8.1 Iphoneos compiled dynamic library, APP foreground call cannot find symbol hint undefined symbols for architecture armv7s reference from. The front desk is theos compiled in the jailbreak development environment.

Suspect: Two connection symbol addresses are different

iOS cross-compiling dylib