Thomas Schatz
The dynamic library (extracted from SDL2-2.0.3.dmg and put in /Library/Frameworks/) references the __Block_copy symbol in /usr/lib/libSystem.B.dylib, which cannot be found:
dlopen(/Library/Frameworks/SDL2.framework/SDL2, 6): Symbol not found: __Block_copy
Referenced from: /Library/Frameworks/SDL2.framework/SDL2
Expected in: /usr/lib/libSystem.B.dylib
From what I could gather __Block_copy seems to be related to the blocks extension to the C programming language introduced by Apple since OSX-10.6 (see: http://thirdcog.eu/pwcblocks/). If this is indeed the case, I don't think the SDL2-2.0.3.dmg on the website is at all compatible with OSX-10.5 countrary to what is announced.