Question

Why do you have to @synthesize in objective C?

Answer 1

You don't. @synthesize automatically generates setters and getters (methods whose names are - (type)variableName and - (void)setVariableName:(type)newValue) for you so that you don't have to write them out yourself.

Answer 2

These can then be used with Key-Value Coding and with the syntactic sugar in Objective-C to do e.g. variable.property = stuff (this transparently becomes a call to [variable setProperty:stuff]).