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  • (转)NSString 类的使用

    温故知新,常用常新
     
    //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。
    复制代码
    NSString *astring = [[NSString alloc] init];

    astring = @"This is a String!";

    [astring release];

    NSLog(@"astring:%@",astring);

    //

    NSString *astring = [[NSString alloc] init];

    NSLog(@"0x%.8x", astring);

    astring=@"This is a String!";

    NSLog(@"0x%.8x", astring);

    [astring release];

    NSLog(@"astring:%@",astring);
    复制代码
     
    //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);

    [astring release];
     
    //4、用标准c创建字符串:initWithCString方法
    复制代码
    char *Cstring = "This is a String!";

    NSString *astring = [[NSString alloc] initWithCString:Cstring];

    NSLog(@"astring:%@",astring);

    [astring release];
    复制代码
     
    //5、创建格式化字符串:占位符(由一个%加一个字符组成)
    复制代码
    int i = 1;

    int j = 2;

    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];

    NSLog(@"astring:%@",astring);

    [astring release];
    复制代码
     
    //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);
    [astring release];
     

    //8、用字符串创建字符串,并写入到文件  

    复制代码
    NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];

    NSLog(@"astring:%@",astring);

    NSString *path = @"astring.text";

    [astring writeToFile: path atomically: YES];

    [astring release];
    复制代码
    注:此路径path只只是示意,真实路径并非如此
     
    //9、用C比较:strcmp函数
    复制代码
    char string1[] = "string!";

    char string2[] = "string!";

    if(strcmp(string1, string2) == 0)
    {

    NSLog(@"1");

    }
    复制代码
     

    //10、isEqualToString方法    

    复制代码
    NSString *astring01 = @"This is a String!";

    NSString *astring02 = @"This is a String!";

    BOOL result = [astring01 isEqualToString:astring02];

    NSLog(@"result:%d",result);
    复制代码
     

    //11、compare方法(comparer返回的三种值)    

    复制代码
    //
    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);
    复制代码
     

    //12、不考虑大小写比较字符串

    复制代码
    //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);
    复制代码
     
    //13、输出大写或者小写字符串
    复制代码
    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
    复制代码
     

    //14、-rangeOfString: //查找字符串某处是否包含其它字符串

    复制代码
    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);

    [astring release];
    复制代码
     

    //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
    复制代码
    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);
    复制代码
     
    //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: 
    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
    复制代码
    NSString *Path = @"~/NSData.txt";

    NSString *absolutePath = [Path stringByExpandingTildeInPath];

    NSLog(@"absolutePath:%@",absolutePath);

    NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
    复制代码
     

    //25、文件扩展名

    NSString *Path = @"~/NSData.txt";

    NSLog(@"Extension:%@",[Path pathExtension]);

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  • 原文地址:https://www.cnblogs.com/lizhitai/p/4485732.html
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