German talk I gave at CocoaHeads Hamburg on 16th May 2013. You need showoff to view it properly. Please use issues and comments to provide feedback.
http://www.friday.com/bbum/2009/12/18/objc_msgsend-part-1-the-road-map/
http://www.friday.com/bbum/2009/12/18/objc_msgsend-tour-part-2-setting-the-stage/
http://www.friday.com/bbum/2009/12/18/objc_msgsend-tour-part-3-the-fast-path/
http://www.friday.com/bbum/2010/02/04/objc_msgsend-tour-part-4-method-lookup-some-odds-and-ends/
http://www.friday.com/bbum/2011/03/17/ios-4-3-imp_implementationwithblock/
http://www.mikeash.com/pyblog/friday-qa-2009-03-13-intro-to-the-objective-c-runtime.html
http://www.mikeash.com/pyblog/friday-qa-2009-03-20-objective-c-messaging.html
http://www.mikeash.com/pyblog/friday-qa-2009-03-27-objective-c-message-forwarding.html
http://www.mikeash.com/pyblog/friday-qa-2009-05-22-objective-c-class-loading-and-initialization.html
http://www.mikeash.com/pyblog/friday-qa-2010-01-29-method-replacement-for-fun-and-profit.html
http://nshipster.com/type-encodings/
http://cocoasamurai.blogspot.de/2010/01/understanding-objective-c-runtime.html
http://blog.metaobject.com/2009/01/simple-hom.html
http://www.phrack.org/issues.html?issue=66&id=4
http://blog.lukhnos.org/post/17270947434/currying-objective-c-methods
http://sealiesoftware.com/blog/archive/2008/10/30/objc_explain_objc_msgSend_stret.html
http://www.sealiesoftware.com/blog/archive/2008/11/16/objc_explain_objc_msgSend_fpret.html