iOS Cookbook1 Objective-C 字符串

从网上搜集汇编的。

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);      [astring release];

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);      NSString *path = @"astring.text";    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];    NSLog(@"astring:%@",astring);      [astring release];      NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];    NSLog(@"astring:%@",astring);      NSString *path = @"astring.text";         [astring writeToFile: path atomically: YES];      [astring release];      

7、字符串比较

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1  

    NSString *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)  


8、如何判断字符串为空  

NSString *urlString = [urlInput stringValue];if (!urlString) {  NSLog( @”NO INPUT.” );} else {     if ([urlString length] == 0 ) {      NSLog( @”NO INPUT.” );   }    else   {    } }

 
9、字符串的替换
注：将字符串中的参数进行替换
参数1：目标替换值
参数2：替换成为的值
参数3：类型为默认：NSLiteralSearch
参数4：替换的范围

[str replaceOccurrencesOfString:@"1" withString:@"222" options:NSLiteralSearch range:NSMakeRange(0, [str length])];   

10、给字符串分配容量

  NSMutableString *String;  String = [NSMutableString stringWithCapacity:40];   

 
11、追加字符串

 NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"]; [String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];     

 
12、在已有字符串中按照所给出范围和长度删除字符

 NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"]; [String1 deleteCharactersInRange:NSMakeRange(0, 5)];     

 
13、在已有字符串后面在所指定的位置中插入给出的字符串

NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];[String1 insertString:@"Hi! " atIndex:0];     

 
14、按照所给出的范围，和字符串替换的原有的字符

 NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"]; [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];     

 
15、判断字符串内是否还包含别的字符串(前缀，后缀)

NSString *String1 = @"NSStringInformation.txt";[String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");[String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");    

 
16、返回一个数组，包含从已经由一个给定的分隔符分为接收器串。
- （NSArray*）componentsSeparatedByString：（NSString*）NString
参数
分离器
分隔符的字符串。

NSString *list = @"Norman, Stanley, Fletcher";NSArray *listItems = [list componentsSeparatedByString:@", "];

listItems包含了：
{ @"Norman", @"Stanley", @"Fletcher" }.
 
17、是否包含该字符串

NSRange range = [@"字符串--A" rangeOfString:“是否包含--B”];if (range.location == NSNotFound){//不包含}else{//包含}