iOS Programming: The Big Nerd Ranch Guide, Second Edition

Fast Enumeration

The newest version of Objective-C added a few syntax changes to the language. One if these is fast enumeration. Before Objective-C 2.0, iterating through an NSArray looked like this:

f​o​r​ ​(​i​n​t​ ​i​ ​=​ ​0​;​ ​i​ ​<​ ​[​i​t​e​m​s​ ​c​o​u​n​t​]​;​ ​i​+​+​)​ ​{​
 ​ ​ ​ ​P​o​s​s​e​s​s​i​o​n​ ​*​i​t​e​m​ ​=​ ​[​i​t​e​m​s​ ​o​b​j​e​c​t​A​t​I​n​d​e​x​:​i​]​;​
 ​ ​ ​ ​N​S​L​o​g​(​@​"​%​@​"​,​ ​i​t​e​m​)​;​
}​

Now you can write that code segment much more succinctly with fast enumeration in main.m.

 ​ ​ ​ ​f​o​r​ ​(​P​o​s​s​e​s​s​i​o​n​ ​*​i​t​e​m​ ​i​n​ ​i​t​e​m​s​)​
 ​ ​ ​ ​ ​ ​ ​ ​N​S​L​o​g​(​@​"​%​@​"​,​ ​i​t​e​m​)​;​ ​ ​ ​ ​[​i​t​e​m​s​ ​r​e​l​e​a​s​e​]​;​ ​ ​ ​ ​i​t​e​m​s​ ​=​ ​n​i​l​;​ ​ ​ ​ ​[​p​o​o​l​ ​d​r​a​i​n​]​;​ ​ ​ ...