iOS NSString的常用用法

openkk 12年前

//1、创建常量字符串。

NSString *astring = @"This is a String!";
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//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);
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//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];
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//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];
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//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];
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//6、创建临时字符串
NSString *astring;     astring = [NSString stringWithCString:"This is a temporary string"];     NSLog(@"astring:%@",astring);
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//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  

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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</div>
 
//9、用C比较:strcmp函数
char string1[] = "string!";   char string2[] = "string!";   if(strcmp(string1, string2) == 0)  {         NSLog(@"1");     }
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//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);
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//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);        
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//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); 
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//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
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//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);
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//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);
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//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);
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//18、-stringWithCapacity: //按照固定长度生成空字符串

NSMutableString *String;     String = [NSMutableString stringWithCapacity:40];
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//19、-appendString: and -appendFormat: //把一个字符串接在另一个字符串的末尾</div>
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);
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//20、-insertString: atIndex: //在指定位置插入字符串</div>
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];     [String1 insertString:@"Hi! " atIndex:0];     NSLog(@"String1:%@",String1);
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//21、-setString: </div>
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];     [String1 setString:@"Hello Word!"];     NSLog(@"String1:%@",String1);
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//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</div> </div>
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];     [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];     NSLog(@"String1:%@",String1);
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//23、-hasPrefix: //检查字符串是否以另一个字符串开头</div>
NSString *String1 = @"NSStringInformation.txt";     [String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");     [String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");
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//24、扩展路径
NSString *Path = @"~/NSData.txt";     NSString *absolutePath = [Path stringByExpandingTildeInPath];     NSLog(@"absolutePath:%@",absolutePath);     NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
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//25、文件扩展名

NSString *Path = @"~/NSData.txt";     NSLog(@"Extension:%@",[Path pathExtension]);

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