Placement of the asterisk in Objective-C

Question

I have just begun learning Objective-C, coming from a VB .Net and C# .Net background. I understand pointer usage, but in Objective-C examples I see the asterisk placed in s

Answer 1

1.  NSString *string;
2.  NSString * string;
3.  (NSString *) string;
4.  NSString* string;

1,2 and 4 are equivalent. The C language (and the Objective-C superset of C) specify a syntax that is insensitive to white space. So you can freely add spaces where you choose as a matter of style. All relevant syntax is delimited by non-whitespace characters (e.g. {, }, ;, etc.) [1].

3 is either a type cast (telling the C compiler to use the NSString* type regardless of the declared type of string. In Objective-C, type casting of object instances is rarely necessary. You can use the id type for variables that can reference instances of any object type.

In method declarations, syntax 3 (sometimes without the ending semicolon) is used to declare the type of method parameters. An Objective-C method may look like this:

- (void)myMethodThatTakesAString:(NSString*)string;

In this declaration, the type of the argument named string is type NSString* (the leading - indicates an instance method as oppose to a class method). A method declaration with more than one parameter might look like this:

- (void)myMethodTakingAString:(NSString*)string andAnInteger:(NSInteger)intParam;

[1] This is compared to languages like Python which use whitespace as a block delimeter.