iOS Components and Frameworks: Understanding the Advanced Features of the iOS SDK

Declaring and Using Blocks

One method of using blocks is to create a block variable, which can be assigned a block and then executed inline in code. A block variable declaration can have a name, can declare parameter types, and can optionally declare a return type (the compiler can infer the return type, but it is good coding form to declare it).

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NSString* (^repeatString) (int, NSString*);

In this case, NSString* at the left of the line of code declares the return type. In parentheses, after the caret symbol (^), repeatString is the name of the declared block. The second set of parentheses declares that two parameters are required for the block, first an int and second an NSString*. After these are declared, the ...