NSString常见用法

1、创建常量字符串
NSString *str = @"Hello World!";

2、创建空字符串，给予赋值
NSString *str = [[NSString alloc] init];
str = @"Hello World!";
[str release];
 

3、initWithString方法
NSString *str = [[NSString alloc] initWithString:@"Hello World!"];
[str release];

4、用标准c创建字符串:initWithCString方法
char *Cstr = "This is a String!";
NSString *str = [[NSString alloc] initWithCString:Cstr];
[str release];

5、创建格式化字符串:占位符%
int i = 1;
int j = 2;
NSString *str = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
[str release];

6、创建临时字符串
NSString *str = [NSString stringWithCString:"Hello World"];

7、从文件创建字符串
NSString *path = [[NSBundlemainBundle] pathForResource:@"str.text"ofType:nil];
NSString *str = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"str:%@",str);
[str release];

8、用字符串创建字符串，并写入到文件
NSString *str = [[NSString alloc] initWithString:@"This is a String!"];
NSString *path = @"str.text";    
[str writeToFile: path atomically: YES];
[str release];

9、isEqualToString方法  
NSString *str01 = @"This is a String!";
NSString *str02 = @"This is a String!";
BOOL result = [str01 isEqualToString:str02];
NSLog(@"result:%d",result);

10、compare方法(comparer返回的三种值)   
 47 //NSOrderedSame判断两者内容是否相同 
NSString *str01 = @"This is a String!";
NSString *str02 = @"This is a String!";   
BOOL result = [str01 compare:str02] == NSOrderedSame;    
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 *str01 = @"This is a String!";
NSString *str02 = @"this is a String!";
BOOL result = [str01 compare:str02] == NSOrderedAscending;    
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)
NSString *str01 = @"this is a String!";
NSString *str02 = @"This is a String!";
BOOL result = [str01 compare:str02] == NSOrderedDescending;    
NSLog(@"result:%d",result); 

11、不考虑大小写比较字符串
NSString *str01 = @"this is a String!";
NSString *str02 = @"This is a String!";
BOOL result = [str01 caseInsensitiveCompare:str02] == NSOrderedSame;    //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，str02小于str01为真)
NSLog(@"result:%d",result); 

NSString *str01 = @"this is a String!";
NSString *str02 = @"This is a String!";
BOOL result = [str01 compare:str02
 
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);

12、输出大写或者小写字符串
NSString *string1 = @"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

13、-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 *str = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
NSLog(@"str:%@",str);
[str release];

14、-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);

15、-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);

16、-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);

17、-stringWithCapacity: 按照固定长度生成空字符串
NSMutableString *String;
String = [NSMutableString stringWithCapacity:20];

18、-appendString: and -appendFormat: 把一个字符串接在另一个字符串的末尾
NSMutableString *str1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
 
[str1 appendString:@", I will be adding some character"];
 
[str1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
 
NSLog(@"str1:%@",str1);

19、-insertString: atIndex: 在指定位置插入字符串
NSMutableString *str1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
 
[str1 insertString:@"Hi! " atIndex:0];
 
NSLog(@"str1:%@",str1);

20、-setString:
NSMutableString *str = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
 
[str setString:@"Hello Word!"];
 
NSLog(@"str:%@",str);


21、-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 *str = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
 
[str replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
 
NSLog(@"str:%@",str);


22、-hasPrefix: 检查字符串是否以另一个字符串开头
NSString *str = @"NSStringInformation.txt";
 
[str hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");
 
[str hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");


23、扩展路径
NSString *Path = @"~/NSData.txt";
 
NSString *absolutePath = [Path stringByExpandingTildeInPath];
 
NSLog(@"absolutePath:%@",absolutePath);
 
NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);


24、文件扩展名
NSString *Path = @"~/NSData.txt";
 
NSLog(@"Extension:%@",[Path pathExtension]);

 // 切割所有的参数
NSArray *array = [str componentsSeparatedByString:@"&"];