【iphone应用开发】NSString的常用用法

//1、创建常量字符串。

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

字符串的长度：

unsigned int length = [astring length]; 

//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:astring02options: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]);