iOS NSString的常用用法

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//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!";
[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]);

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