Objective-C中的For和ForEach迴圈（For and ForEach Loops in Objective-C ）

原文地址：http://howtomakeiphoneapps.com/2009/05/for-and-foreach-loops-in-objective-c/

 

 

Loops are the gears of programming: they make your code take action.

The two loops I use most often is the for loop (to do a predefined number of steps) and what is usually called a foreach loop (to move though a list of objects).

//This loop simply repeats an action
//a set amount of times:
for (int i=0; i<=3; i++)
NSLog([NSString stringWithFormat:@"i=%i", i]);

//Create an array of strings for the next example:
NSMutableArray *bunchOfThings = [[NSMutableArray alloc] init];
[bunchOfThings addObject:@"Zero"];
[bunchOfThings addObject:@"One"];
[bunchOfThings addObject:@"Two"];
[bunchOfThings addObject:@"Three"];

//This is sometimes called a "for each" loop
//Using this list will repeat actions for each
//object in a list.
//Hint: you can use this for any type of list of
//objects so if you have list of custom defined
//objects this is an easy way to work with them all
//at one time.
for(NSString *s in bunchOfThings)
NSLog([NSString stringWithFormat:@"s=%@", s]);

 

 

//The array must be released since it was alloc/init earlier.
[bunchOfThings release];