1. componentsSeparatedByString 将字符串切割成数组
NSString *a = [[NSString alloc] initWithString : @"狗，猪，苹果，小狗" ];
NSArray *b = [a componentsSeparatedByString:@"，"];
NSString *c = [b objectAtIndex:2];
NSLog(@"\n b的index是2的值为： %@", c);
输出为 苹果
原文：http://www.cnblogs.com/ITliufei/p/5734260.html