iOS NSString的常用用法

//2、创建空字符串，给予赋值。

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);

//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

char *Cstring = 'This is a String!'; NSString *astring = [[NSString alloc] initWithCString:Cstring]; NSLog(@'astring:%@',astring); [astring release];

//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); [astring release];

//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  

NSString *astring = [[NSString alloc] initWithString:@'This is a String!']; NSLog(@'astring:%@',astring); NSString *path = @'astring.text'; [astring writeToFile: path atomically: YES]; [astring release];

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

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); [astring release];

//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: 

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]);