1. Methods and Messages
a) class method - call it by sending a message to the class itself
b) instance method - call it by sending a message to an instance of the class
An Objective-C method’s name must contain exactly as many colons as the method
takes parameters, and, the parameter name must end with a colon
c) Calling a Method
eg:
NSString* s = @"Hello, world!";
NSString* s2 = [s uppercaseString];
<=>
NSString* s2 = [@"Hello, world!" uppercaseString];
//If a method takes no parameters, then its name contains no colons
//If a method takes two or more parameters, its name contains that number of colons
eg:
[someObject hereAreThreeStrings: @"string1" : @"string2" : @"string3"];