Continuation Passing Style, or CPS, is a style of programming using anonymous functions to replace return statements. Instead of returning a value, a function will take another function as a parameter. Then, when it gets to the point where it would have returned a value, it calls the passed-in function with the value as a parameter instead.
In Objective-C, we now have anonymous functions in the form of blocks, so CPS can be achieved using blocks.
Here's an example of how CPS looks. This is the standard-style code:
NSString *string = [obj stringWhatever];
// use string
And here it is converted to Continuation Passing Style:
[obj stringWhatever: ^(NSString *string) {
// use string
}];