NSting类与NSMutableString类中常用方法

NString类的一些方法:

一.创建对象

       两种方式:

    1.便利构造器(+号)
        NSString *str1 = [NSString stringWithFormat:@"Frank is handsome %dboy",56];
        NSLog(@"%@",str1);
   2.  alloc +初始化方法
        NSString *str2 = [[NSString alloc] initWithFormat:@"iphone%d",4];
        NSLog(@"%@",str2);

求字符串长度
        NSUInteger length = [str1 length];
        NSLog(@"length  =  %lu",length);

获取字符串中某个字符
        unichar cha = [str1 characterAtIndex:2];

判断是否以指定的字符串开头,或者以指定的字符串结尾
        例如:判断一个字符串是否以http开头,以.com结束
       NSString *str4 = [[NSString alloc]initWithFormat:@"http://www.baidu.com"];
        判断是否以http开头
           BOOL isPrefix =  [str4 hasPrefix:@"http"];
        判断是否以.com结尾
        BOOL isSuffix = [str4 hasSuffix:@".com"];
        NSLog(@"isPrefix = %d,isSuffix = %d",isPrefix,isSuffix);

查找指定字符串的范围
        NSRange range = [str4 rangeOfString:@"ww"];
        if (range.length==0) {
            NSLog(@"没有找到对应字符串");
        }else{
            将NSRange类型的结构体变量转变成字符串对象
            NSLog(@"%@",NSStringFromRange(range));
        }

字符串截取(获取子字符串)
        NSString *str5 = [NSString stringWithFormat:@"laoousa"];
        //1.获取给定的下标之后的子串,,包含指定下标对应的字符:例如:获取sa
        NSString *subString1 = [str5 substringFromIndex:5];
        NSLog(@"%@",subString1);
        //2.获取给定下标之前的子串,从下标为0开始,但是不包括指定下标对应的字符:例如:获取lanou
        NSString *subString2 = [str5 substringToIndex:5];
        NSLog(@"%@",subString2);
        //3.获取指定范围内的子串:例如:获取ou
        NSString *subString3 = [str5 substringWithRange:NSMakeRange(3, 2)];
        NSLog(@"%@",subString3);*/

字符串拼接
        NSString *str6 = [NSString stringWithFormat:@"lanou"];
        //1.lanou  后拼接 henan
        NSString *newStr6 = [str6 stringByAppendingString:@"henan"];
        NSLog(@"%@",newStr6);
        //2.lanou  后拼接 henan9ban
      //  NSString *newStr7 = [str6 stringByAppendingFormat:@"henan%dban",9];
        NSString *newStr7 = [str6 stringByAppendingFormat:@"%@",newStr6];
        NSLog(@"%@",newStr7);

替换字符串
        NSString *str8 = [NSString stringWithFormat:@"lanououuisbig"];
        //1.将ou替换成牛B
        NSString *newStr = [str8 stringByReplacingOccurrencesOfString:@"ou" withString:@"牛B"];
        NSLog(@"%@",newStr);
        //2.只将一个ou替换成牛B
        NSString *newStr1 = [str8 stringByReplacingCharactersInRange:NSMakeRange(3, 2) withString:@"牛B"];
        NSLog(@"%@",newStr1);         

字符串比较
  字符串比较

        NSComparisonResult result = [@"3261" compare:@"3222"];
        NSLog(@"%ld",result);

字符串和数值类型转换
        //1.将字符串@"123",将字符串123转换成整数123
        //从第一个字符开始,如果遇到除了空格之外的字符时,将前面的空格忽视掉,继续往下找,读取数字,直到遇到非数字时结果
        int value = [@"123"  intValue];
        NSLog(@"%d",value);

字符串大小写转换
        //1.将@"lan  ou"  全部转为大写
        NSString *upperString = [@"lan ou" uppercaseString];
        NSLog(@"%@",upperString);
        //2.将@"lan  ou"  全部转为小写
        NSString *upperString1 = [@"lAn oU" lowercaseString];
        NSLog(@"%@",upperString1);
        //3.将@"lan  ou"  每个单词首字母大写
        NSString *upperString2 = [@"lan  ou" capitalizedString];
        NSLog(@"%@",upperString2); 

二.NSMutableString  类的一些方法

   NSMutableString *str = [NSMutableString stringWithFormat:@"lanouhenan"];

        // 对于可变字符串的增删改方法,都是在原字符串基础上进行修改,所以修改之后原字符串的内容发生变化,所以无需返回值
 1.在原字符串基础上拼接Frank
        [str appendString:@"frank"];
        NSLog(@"%@",str);
  2.在字符串str基础上拼接Frank
        [str appendFormat:@"%@",@"frank"];
        NSLog(@"%@",str);
  删除字符串,在原字符串基础上删除henan
        [str deleteCharactersInRange:NSMakeRange(0, 5)];
        NSLog(@"%@",str);
 插入字符串,在原字符串基础上插入lanou
        [str insertString:@"lanou" atIndex:0];
        NSLog(@"%@",str);
 替换字符串,在原字符串基础上,将第一个frank替换成duck
        [str replaceCharactersInRange:NSMakeRange(10, 5) withString:@"duck"];
        NSLog(@"%@",str);