NSString 基本用法

原文：

http://www.cnblogs.com/lovekarri/articles/2380033.html

http://blog.sina.com.cn/s/blog_801997310101gipe.html

1、创建常量字符串

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

 2、创建空字符串，再给予赋值

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、用initWithString方法提升速度:

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    

复制代码

NSString *astring01 = @"This is a String!";
 NSString *astring02 = @"This is a String!";
 BOOL result = [astring01 isEqualToString:astring02];
 NSLog(@"result:%d",result);

11、考虑大小写比较2个字符串

void compareString() {  
  NSComparisonResult result = [@"bmn" compare:@"azz"];
    if (result == NSOrderedSame) {
        NSLog(@"左 ＝＝ 右");
    }else if (result == NSOrderedDescending) {
        NSLog(@"左 > 右");
    }else if (result == NSOrderedAscending)
    {
        NSLog(@"左 <</span> 右");
    }
    
}

 12、不考虑大小写比较字符串

void compareString() {  
    NSComparisonResult caseInsenresult = [@"dffA" caseInsensitiveCompare:@"dffa"];    if (caseInsenresult == NSOrderedSame) {        NSLog(@"左 ＝＝ 右");    }else if (caseInsenresult == NSOrderedDescending) {        NSLog(@"左 > 右");    }else if (caseInsenresult == NSOrderedAscending)    {        NSLog(@"左 <</span> 右");    }
    
}

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

查找字符串中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);
if (range.location == NSNotFound) {
        NSLog(@"str中没有找到 567");
    }else {
        NSLog(@"搜索范围 %@",NSStringFromRange(range));
    }
    // 或者
//    if (range.length == 0 ) {
//        NSLog(@"str中没有找到 567");
//    }
[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与-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、取文件扩展名

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

  

结束！