OC中字符串的提取与替换-四种不同方法实现

/*
1.将可变字符串 @"When I was young, I loved a girl in neighbor class."中,从 young提取到girl。替换 成@"a teacher, I rather to teach student "。
*/

/*方法一*/
//NSMutableString * str = @"When I was young, I loved a girl in neighbor class.";
/*
NSMutableString * str1 = [[NSMutableString alloc]initWithString:@"When I was young, I loved a girl in neighbor class."];
[str1 replaceCharactersInRange:NSMakeRange(11, 21) withString:@"a teacher, I rather to teach student"];
NSLog(@"%@",str1);
*/

/**方法二  先删除 再插入*/
/*
NSMutableString * str1 = [[NSMutableString alloc]initWithString:@"When I was young, I loved a girl in neighbor class."];
[str1 deleteCharactersInRange:NSMakeRange(11,22)];
//NSLog(@"%@",str1);
[str1 insertString:@"a teacher, I rather to teach student" atIndex:11];
NSLog(@"%@",str1);
*/

/*方法三*/
/*
NSMutableString * str1 = [[NSMutableString alloc]initWithString:@"When I was young, I loved a girl in neighbor class."];
NSString * str2 = [str1 stringByReplacingOccurrencesOfString:@"young, I loved a girl" withString:@"a teacher, I rather to teach student"];
NSLog(@"%@",str2);
*/

/*方法四*/
NSMutableString * str1 = [[NSMutableString alloc]initWithString:@"When I was young, I loved a girl in neighbor class."];
NSMutableString * str2=[str1 stringByReplacingOccurrencesOfString:@"young, I loved a girl" withString:@""];
[str2 insertString:@"a teacher, I rather to teach student" atIndex:11];
NSLog(@"%@",str2);