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***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
}