iOS NSString的常用用法(史上最全)

时间:2022-08-25 16:44:20
  NSString *str1 = @"BeiJing";
    NSString *str2 = @"beijing";
    
    //全部转为大写
    NSLog(@"%@",[str1 uppercaseString]);
    
    //全部转为小写
    NSLog(@"%@",[str1 lowercaseString]);
    
    //首字母大写
    NSLog(@"%@",[str1 capitalizedString]);
    
    //比较两个字符串内容是否相同
    BOOL b =[str1 isEqualToString:str2];
    
    //5.两个字符串内容比较
    //NSOrderedAscending    右边 > 左边
    //NSOrderedSame         内容相同
    //NSOrderedDescending   左边 > 右边
    NSComparisonResult result = [str1 compare:str2];
    if (result == NSOrderedAscending) {
        NSLog(@"右边 > 左边");
    }else if(result == NSOrderedSame){
        NSLog(@"内容相同");
    }else if (result == NSOrderedDescending){
        NSLog(@"左边 > 右边");
    }
    
    //忽略大小写进行比较,返回值与compare一样
    result = [str1 caseInsensitiveCompare:str2];
    if (result == NSOrderedAscending) {
        NSLog(@"右边 > 左边");
    }else if(result == NSOrderedSame){
        NSLog(@"内容相同");
    }else if (result == NSOrderedDescending){
        NSLog(@"左边 > 右边");
    }
    
    //判断字符串是否以指定字符串开头
    [str1 hasPrefix:@"aaa"];
    //判断字符串是否以指定字符串结尾
    [str1 hasSuffix:@"aaa"];
    
    //判断字符串是否包含指定字符串,返回位置和长度
    NSRange range = [@"123456" rangeOfString:@"456"];
    NSLog(@"%@", NSStringFromRange(range));
    
    //反向搜索
    range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch];
    NSLog(@"%@",NSStringFromRange(range));
    
    //指定范围进行搜索
    range = NSMakeRange(0, 9);
    range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch range:range];
    NSLog(@"%@",NSStringFromRange(range));
    
    //字符串的截取
    NSString *str = @"123456789";
    NSLog(@"%@",[str substringFromIndex:3]);
    NSLog(@"%@",[str substringToIndex:6]);
    NSLog(@"%@",[str substringWithRange:NSMakeRange(3, 3)]);
    
    //用指定字符串分割字符串,返回一个数组
    NSArray *array = [@"1,2,3,4,5,6" componentsSeparatedByString:@","];
    NSLog(@"%@",array);
    
    //将数组中的字符串组合成一个文件路径
    NSMutableArray *components = [NSMutableArray array];
    [components addObject:@"Users"];
    [components addObject:@"CentralPerk"];
    [components addObject:@"Desktop"];
    NSString *path = [NSString pathWithComponents:components];
    NSLog(@"%@",path);  //Users/CentralPerk/Desktop
    
    //将一个路径分割成一个数组
    NSArray *array1 = [path pathComponents];
    NSLog(@"%@",array1);
    
    //判断是否为绝对路径(依据:是否以'/'开始)
    path = @"/Users/CentralPerk/Desktop";
    NSLog(@"%i",[path isAbsolutePath]);
    
    //获取最后一个目录
    NSLog(@"%@",[path lastPathComponent]);
    
    //删除最后一个目录
    NSLog(@"%@",[path stringByDeletingLastPathComponent]);
    
    //拼接一个目录
    NSLog(@"%@",[path stringByAppendingPathComponent:@"aaa"]);   ///Users/CentralPerk/Desktop/aaa
    NSLog(@"%@",[path stringByAppendingString:@"aaa"]);      ///Users/CentralPerk/Desktopaaa
    NSLog(@"%@",[path stringByAppendingFormat:@"%@%@",@"b",@"c"]);  ///Users/CentralPerk/Desktopbc
    
    //拓展名出来
    //获取拓展名,不带.
    NSString *str3 = @"Users/CentralPerk/Desktop/test.txt";
    NSLog(@"%@",[str3 pathExtension]);
    //添加拓展名,不需要带.
    NSLog(@"%@",[str3 stringByAppendingPathExtension:@"mp3"]);
    //删除拓展名,带.一块删除
    NSLog(@"%@",[str3 stringByDeletingPathExtension]);
    
    //字符串转为 int double float
    NSString *str4 = @"123";
    NSLog(@"%i",[str4 intValue]);
    NSLog(@"%zi",[str4 length]);
    
    //取出指定位置的字符
    unichar c = [str4 characterAtIndex:2];
    NSLog(@"%c",c);
    
    //转为C语言的字符串
    const char *s = [str4 UTF8String];
    NSLog(@"%s",s);
    
    //去掉两端的空格
    [str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    
    //去掉多余的空格
    NSString *str = @"    this     is a    test    .   ";
    NSCharacterSet *whitespaces = [NSCharacterSet whitespaceCharacterSet];
    NSPredicate *noEmptyStrings = [NSPredicate predicateWithFormat:@"SELF != ''"];
    NSArray *parts = [str componentsSeparatedByCharactersInSet:whitespaces];
    NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];
    str = [filteredArray componentsJoinedByString:@" "];
    
    //去掉所有空格
    [str stringByReplacingOccurrencesOfString:@" " withString:@""]
    
    
    
    
    
    
    
    
    //1、创建常量字符串。
    NSString *astring = @"This is a String!";
    
    
    //2、创建空字符串,给予赋值。
    NSString *astring = [[NSString alloc] init];
    astring = @"This is a String!";
    NSLog(@"astring:%@",astring);
    
    //
    NSString *astring = [[NSString alloc] init];
    NSLog(@"0x%.8x", astring);
    astring=@"This is a String!";
    NSLog(@"0x%.8x", astring);
    NSLog(@"astring:%@",astring);
    
    
    //3、在以上方法中,提升速度:initWithString方法
    NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
    NSLog(@"astring:%@",astring);
    
    
    //4、用标准c创建字符串:initWithCString方法
    char *Cstring = "This is a String!";
    NSString *astring = [[NSString alloc] initWithCString:Cstring];
    NSLog(@"astring:%@",astring);
    
    //5、创建格式化字符串:占位符(由一个%加一个字符组成)
    int i = 1;
    int j = 2;
    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
    NSLog(@"astring:%@",astring);
    
    //6、创建临时字符串
    NSString *astring;
    astring = [NSString stringWithCString:"This is a temporary string"];
    NSLog(@"astring:%@",astring);
    
    
    
    //7、从文件创建字符串
    NSString *path = [[NSBundlemainBundle] pathForResource:@"astring.text"ofType:nil];
    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
    NSLog(@"astring:%@",astring);
    
    
    //8、用字符串创建字符串,并写入到文件
    NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
    NSLog(@"astring:%@",astring);
    NSString *path = @"astring.text";//注:此路径path只只是示意,真实路径并非如此
    [astring writeToFile: path atomically: YES];
    
    
    //9、用C比较:strcmp函数
    char string1[] = "string!";
    char string2[] = "string!";
    if(strcmp(string1, string2) == 0){
        NSLog(@"1");
    }
    
    
    
    //10、isEqualToString方法
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 isEqualToString:astring02];
    NSLog(@"result:%d",result);
    
    
    
    //11、compare方法(comparer返回的三种值)
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02] == NSOrderedSame;    //NSOrderedSame判断两者内容是否相同
    NSLog(@"result:%d",result);
    //
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"this is a String!";
    BOOL result = [astring01 compare:astring02] == NSOrderedAscending;    //NSOrderedAscending判断两对象值的大小(按字母顺序进行比较,astring02大于astring01为真)
    NSLog(@"result:%d",result);
    
    //
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02] == NSOrderedDescending;    //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较,astring02小于astring01为真)
    NSLog(@"result:%d",result);
    
    
    
    
    //12、不考虑大小写比较字符串
    //1.
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 caseInsensitiveCompare:astring02] == NSOrderedSame;    //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较,astring02小于astring01为真)
    NSLog(@"result:%d",result);
    
    //2.
    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02
                   
                             options:NSCaseInsensitiveSearch | NSNumericSearch] == NSOrderedSame;    //NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较,区分大小写 NSNumericSearch:比较字符串的字符个数,而不是字符值。
    NSLog(@"result:%d",result);
    
    
    //13、输出大写或者小写字符串
    NSString *string1 = @"A String";
    NSString *string2 = @"String";
    NSLog(@"string1:%@",[string1 uppercaseString]);//大写
    NSLog(@"string2:%@",[string2 lowercaseString]);//小写
    NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小
    
    
    
    //14、-rangeOfString: //查找字符串某处是否包含其它字符串
    NSString *string1 = @"This is a string";
    NSString *string2 = @"string";
    NSRange range = [string1 rangeOfString:string2];
    int location = range.location;
    int leight = range.length;
    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
    NSLog(@"astring:%@",astring);
    
    
    
    //15、-substringToIndex: 从字符串的开头一直截取到指定的位置,但不包括该位置的字符
    NSString *string1 = @"This is a string";
    NSString *string2 = [string1 substringToIndex:3];
    NSLog(@"string2:%@",string2);
    
    
    
    //16、-substringFromIndex: 以指定位置开始(包括指定位置的字符),并包括之后的全部字符
    NSString *string1 = @"This is a string";
    NSString *string2 = [string1 substringFromIndex:3];
    NSLog(@"string2:%@",string2);
    
    
    
    //17、-substringWithRange: //按照所给出的位置,长度,任意地从字符串中截取子串
    NSString *string1 = @"This is a string";
    NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
    NSLog(@"string2:%@",string2);
    
    
    
    //18、-stringWithCapacity: //按照固定长度生成空字符串
    NSMutableString *String;
    String = [NSMutableString stringWithCapacity:40];
    
    
    //19、-appendString: and -appendFormat: //把一个字符串接在另一个字符串的末尾
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 appendString:@", I will be adding some character"];
    [String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
    NSLog(@"String1:%@",String1);
    
    
    //20、-insertString: atIndex: //在指定位置插入字符串
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 insertString:@"Hi! " atIndex:0];
    NSLog(@"String1:%@",String1);
    
    
    //21、-setString:  替换字符串
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 setString:@"Hello Word!"];
    NSLog(@"String1:%@",String1);
    
    
    //22、-replaceCharactersInRange: withString: //用指定字符串替换字符串中某指定位置、长度的字符串
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
    NSLog(@"String1:%@",String1);
    
    
    //23、-hasPrefix: //检查字符串是否以另一个字符串开头
    NSString *String1 = @"NSStringInformation.txt";
    [String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");
    [String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");
    
    
    //24、扩展路径
    NSString *Path = @"~/NSData.txt";
    NSString *absolutePath = [Path stringByExpandingTildeInPath];
    NSLog(@"absolutePath:%@",absolutePath);
    NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
    
    
    
    //25、文件扩展名
    NSString *Path = @"~/NSData.txt";
    NSLog(@"Extension:%@",[Path pathExtension]);
    
    
    //26、剪切 字符串 ,按照range的要求,从第几个开始 , 剪切的长度为几
    NSMutableString *a = [[NSMutableString  alloc] initWithString:@"123456798"];
    NSLog(@" \n a:  %@ \n",a);
    [a deleteCharactersInRange:NSMakeRange(1, 2)];
    NSLog(@" \n a:  %@ \n",a);
    //    2011-07-05 20:59:34.169 Q[9069:207]    a:  123456798
    //    2011-07-05 20:59:34.171 Q[9069:207]    a:  1456798