Object-c之不可变字符串 常用方法

    // 01.创建不可变字符串

    NSString *str =[NSStringstring];// 空字符串对象

    NSLog(@"str= %@", str);

    NSString *str1 =@"此字符串存放于常量区";

    NSLog(@"str1= %@",str1);

    // 输出: str = (空) str1 =此字符串存放于常量区

       

    //02.格式化创建字符串(类方法)

    NSString *str2 =[NSStringstringWithFormat:@"%s%f","hello",5.2];

    NSLog(@"str2= %@", str2);

    // 输出: str1 = hello5.200000

   

    //03.利用C语言的字符串生成OC的字符串对象

    NSString *str3 =[NSStringstringWithUTF8String:"welloc中国"];

    NSLog(@"str3= %@", str3);

    // 输出: str3 = welloc中国

       

    //04.将一个字符串复制到另一字符串

    NSString *str4 =[NSStringstringWithString:str3];

    NSLog(@"str4= %@", str4);

    // 输出: str4 = welloc中国

       

    //05.把网址内容生成字符串对象

    NSURL *url =[NSURLURLWithString:@"http://fuli.ba"];

    NSString *str5 =[NSStringstringWithContentsOfURL:urlencoding:NSUTF8StringEncoding   error:nil];  

    NSLog(@"%@", str5);

       

    //06.把文件内容生成字符串对象

    NSString *str6 =[NSStringstringWithContentsOfFile:@"/Users/fuck/1.html"encoding:NSUTF8StringEncodingerror:nil];

    NSLog(@"%@", str6);

    

    /*********************字符串相关操作************************/

      NSString *str01= @"hello world";

      NSString *str11= @"hello china";

       

    //获取字符串长度

    NSLog(@"len= %li",[str01length]);

    // 输出: len = 11

       

    //获取指定位置的字符

    unichar ch =[str01 characterAtIndex:1];

    NSLog(@"ch= %C", ch);//大写C

    // 输出: ch = e

       

    //提取字符串方法(从索引位置提取子串到字符串末尾)

    NSString *str02= [str01 substringFromIndex:6];

    NSLog(@"str02= %@",str02);//从0开始

    // 输出: str02 = world

       

    //从字符串的开始位置提取子串到索引位置,不包含索引位置的字符

    NSString *str03= [str01 substringToIndex:7];

    NSLog(@"str03= %@",str03);

    // 输出: str03 = hello w

       

    //提取指定范围内的字符串

    NSString *str04= [str01 substringWithRange:NSMakeRange(6,3)];

    NSLog(@"str04= %@",str04);

    // 输出: str04 = wor

       

    //判断两个字符串是否相等

    BOOL ret1 =[str01 isEqualToString:str11];

    NSLog(@"ret1= %i", ret1);//相等返回yes(1)

    // 输出: ret1 = 0

       

   

    //两个字符串比较

    NSComparisonResult ret2 =[str01compare:str11];

    NSLog(@"ret2= %li", ret2);

    // 输出: ret2 = 1

       

    //追加字符串(不是直接修改原字符串)

    NSString *str05= [str01 stringByAppendingString: @"fuck you world ~ ~ ~"];

    NSLog(@"str05= %@",str05);

    // 输出: str05 = hello world fuck you world ~ ~~u438

       

    //格式化追加字符串(66也没改变)

    NSString *str06= [str05 stringByAppendingFormat:@"%c%d", 'u', 438];

    NSLog(@"str06= %@", str06);

    // 输出: str06 = hello world fuck you world ~ ~ ~

       

    //正序字符串查找

    NSRange range1= [str05 rangeOfString:@"world"];

    NSLog(@"location1= %li length1 = %li",range1.location,range1.length);

    // 输出: location1 = 6 length1 = 5

       

    //倒序字符串查找

    NSRange range2= [str05 rangeOfString:@"world" options:NSBackwardsSearch];

    NSLog(@"location2= %li length2 = %li",range2.location,range2.length);

    // 输出: location2 = 21 length2 = 5

       

    //把数字字符串转化成数字

    int a = [@"123"intValue];

    NSLog(@"a= %i",a);

    float b = [@"00.254"floatValue];

    NSLog(@"b= %f", b);

    // 输出: a =123 b = 0.254000

       

   

 

    //大小写转换

    NSLog(@"%@",[@"helloworld"uppercaseString]);

    NSLog(@"%@",[@"HELLOWORLD"lowercaseString]);

    // 输出: HELLO WORLD hello world

       

    //把每个单词的首字母转换成大写,其余小写

    NSLog(@"%@",[@"hElloworlD"capitalizedString]);

    // 输出: Hello World

       

    //字符串替换

    NSString *str07= [@"hello world hello world "stringByReplacingOccurrencesOfString:@"hello"withString:@"hi"];

    NSLog(@"str07= %@", str07);

    // 输出: str07 = hi world hi world

 //以字符串整体分割

NSString *str = @" #I #am Prime  # # #Optimus";

NSArray *dstArray = [str componentsSeparatedByString:@" #"];

NSLog(@"dstArray = %@", dstArray);

NSMutableArray *mulArray = [NSMutableArrayarrayWithArray:dstArray];

[mulArray removeObject:@""];

NSLog(@"mulArray = %@", mulArray);

//输出 : dstArray = ("",I,"am Prime","","",Optimus)

//输出 : mulArray = (I,"am Prime ",Optimus)

 

 

//以字符集分割字符串

NSArray *dstArray2 = [str componentsSeparatedByCharactersInSet:[NSCharacterSetcharacterSetWithCharactersInString:@"# "] ];

NSLog(@"dstArray2 = %@", dstArray2);

NSMutableArray *mulArray2 = [NSMutableArrayarrayWithArray:dstArray2];

[mulArray2 removeObject:@""];

NSLog(@"mulArray2 = %@", mulArray2);

//输出 : dstArray2 =("","",I,"",am,Prime,"","","","","","",Optimus)

//输出 : mulArray2 = (I,am,Prime,Optimus)