When to use a colon with a @selector

Question

Just getting going with iPhone development and Objective-C.

Yesterday I was trying to addObserver for a notification in a view of mine, and I kept getti

Answer 1

The colon indicates that the method takes a parameter.

[someObject performSelector:@selector(doSomething:)] means that doSomething is expecting a parameter.

[someObject performSelector:@selector(doSomething)] means that doSomething doesn't need any parameters.