可变字符串

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        //NSString是父类  可变字符串是子类

        NSMutableString *mustr=[[NSMutableString alloc]init];

        //将不可变的字符串放置到可变的字符串内

        NSString *str=@"Welcome to oc";

        mustr=[NSMutableString stringWithString:str];

    //插入

        [mustr insertString:@" student " atIndex:7];//在具体的位置插入

        [mustr appendString:@" teacher "];//在末尾插入

        NSLog(@"%@",mustr);

        [mustr appendFormat:@"第二遍插入:%@",str];//格式化插入

        NSLog(@"%@",mustr);

    //删除

        [mustr deleteCharactersInRange:NSMakeRange(8, 9)];//根据位置删除

        NSLog(@"%@",mustr);

    //查找并删除

        NSRange rang=[mustr rangeOfString:@"第二遍插入:Welcome to oc"];

        if (rang.location!=NSNotFound) {

            [mustr deleteCharactersInRange:rang];

        }

        NSLog(@"%@",mustr);

    //重新赋值

        [mustr setString:str];

        NSLog(@"%@",mustr);

        

    //替换

        NSRange rang1=[mustr rangeOfString:@"oc"];

        [mustr replaceCharactersInRange: rang1 withString:@"ios"];

        NSLog(@"%@",mustr);

        

        NSMutableString *num=[[NSMutableString alloc]initWithString:@"233-343-123-000"];

        NSRange rang2=[num rangeOfString:@"-"];

        [num replaceCharactersInRange:rang2 withString:@""];

        NSLog(@"%@",num);

        NSString *newnum=[NSString string];

        newnum=[num stringByReplacingOccurrencesOfString:@"-" withString:@""];

        NSLog(@"%@",newnum);

    }

    return 0;

}