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);