NSString 字符串操作

//一、NSString/*----------------创建字符串的方法----------------*/ //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); //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);/*----------------从文件读取字符串:initWithContentsOfFile方法----------------*/NSString *path = @"astring.text";NSString *astring = [[NSString alloc] initWithContentsOfFile:path];NSLog(@"astring:%@",astring);/*----------------写字符串到文件:writeToFile方法----------------*/NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];NSLog(@"astring:%@",astring);NSString *path = @"astring.text";[astring writeToFile: path atomically: YES];/*----------------比较两个字符串----------------*///用C比较:strcmp函数char string1[] = "string!";char string2[] = "string!";if(strcmp(string1, string2) = = 0){NSLog(@"1");}//isEqualToString方法NSString *astring01 = @"This is a String!";NSString *astring02 = @"This is a String!";BOOL result = [astring01 isEqualToString:astring02];NSLog(@"result:%d",result);//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;NSLog(@"result:%d",result);//NSOrderedSame判断两者内容是否相同NSString *astring01 = @"This is a String!";NSString *astring02 = @"this is a String!";BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;NSLog(@"result:%d",result);//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)NSString *astring01 = @"this is a String!";NSString *astring02 = @"This is a String!";BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;NSLog(@"result:%d",result);//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)//不考虑大小写比较字符串1NSString *astring01 = @"this is a String!";NSString *astring02 = @"This is a String!";BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;NSLog(@"result:%d",result);//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)//不考虑大小写比较字符串2NSString *astring01 = @"this is a String!";NSString *astring02 = @"This is a String!";BOOL result = [astring01 compare:astring02options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;NSLog(@"result:%d",result);//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。/*----------------改变字符串的大小写----------------*/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/*---------------在串中搜索子串----------------*/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];/*----------------抽取子串 ----------------*///-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);//-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);//-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);//扩展路径NSString *Path = @"~/NSData.txt";NSString *absolutePath = [Path stringByExpandingTildeInPath];NSLog(@"absolutePath:%@",absolutePath);NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);//文件扩展名NSString *Path = @"~/NSData.txt";NSLog(@"Extension:%@",[Path pathExtension]);/*******************************************************************************************NSMutableString*******************************************************************************************//*---------------给字符串分配容量----------------*///stringWithCapacity:NSMutableString *String;String = [NSMutableString stringWithCapacity:40];/*---------------在已有字符串后面添加字符----------------*///appendString: and appendFormat: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);*//*--------在已有字符串中按照所给出范围和长度删除字符------*//*//deleteCharactersInRange:NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];[String1 deleteCharactersInRange:NSMakeRange(0, 5)];NSLog(@"String1:%@",String1);/*--------在已有字符串后面在所指定的位置中插入给出的字符串------*///-insertString: atIndex:NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];[String1 insertString:@"Hi! " atIndex:0];NSLog(@"String1:%@",String1);/*--------将已有的空符串换成其它的字符串------*///-setString:NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];[String1 setString:@"Hello Word!"];NSLog(@"String1:%@",String1);/*--------按照所给出的范围，和字符串替换的原有的字符------*///-setString:NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];NSLog(@"String1:%@",String1);/*-------------判断字符串内是否还包含别的字符串(前缀，后缀)-------------*///01：检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;NSString *String1 = @"NSStringInformation.txt";[String1 hasPrefix:@"NSString"] = = 1 ?NSLog(@"YES") : NSLog(@"NO");[String1 asSuffix:@".txt"] = = 1 ?NSLog(@"YES") : NSLog(@"NO");//02：查找字符串某处是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过;