NSString 对象类型

一个NSString对象可以存储一段Unicode字符。在cocoa中，所有和字符、字符串相关的处理都是使用NSString来完成。
NSObject -> NSString // NSString继承自NSObject

+(id) stringWithContentsOfFile:path encoding:enc error:err;
+(id) stringWithContentsOfURL:url encoding:enc error:err;
+(id) stringWithString:nsstring;   //创建一个新的字符串，并将其设置为nsstring
-(id)initWithFormat:(NSString *)format, ...  ;
-(id)initWithString:nsstring;     //将分配的字符串设置为nsstring
- (BOOL)isEqualToString:(NSString *)string;
- (BOOL)hasPrefix:(NSString *)string;
- (int)intValue;
- (double)doubleValue;
- (NSString *)stringByAppendingString:(NSString *)string;  // 给一个字符串附加一个字符串string。
- (NSString *)stringByAppendingFormat:(NSString *)string;
- (NSString *)stringByDeletingPathComponent;

-----创建字符串的方法-----
//1、创建常量字符串

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

//2、先创建一个空的字符串，然后赋值；
// alloc和init组合则适合在函数之间传递参数

    NSString *astring = [[NSString alloc] init];  
    astring = @"This is a String!"; 
    NSLog(@"astring:%@",astring); 

//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); 

//4、创建临时字符串

    NSString *astring; 
    astring = [NSString  stringWithCString:"This is a temporary string"]; 
    NSLog(@"astring:%@",astring);
// OR
    NSString *  scriptString = [NSString stringWithString:@" tell application \"Mail\"\r"];

//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); 

-----从文件读取字符串-----

    NSString *path = @"astring.text";
    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
    NSLog(@"astring:%@",astring);

-----写字符串到文件----

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

-----比较两个字符串-----
//1、用C比较:strcmp函数

    char string1[] = "string!";
    char string2[] = "string!";
    if(strcmp(string1, string2) = = 0)
    {
        NSLog(@"1");
    }

//2、isEqualToString方法

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

//3、compare方法(comparer返回的三种值：NSOrderedSame，NSOrderedAscending，NSOrderedDescending)

    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;   
    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)

//4、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)

//5、不考虑大小写比较字符串2

    NSString *astring01 = @"this is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 compare:astring02
                            options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;   
    NSLog(@"result:%d",result);     
    //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。

-----改变字符串的大小写-----

    NSString *string1 = @"A String";
    NSString *string2 = @"String";
    NSLog(@"string1:%@",[string1 uppercaseString]);//uppercaseString返回转换为大写的字符串
    NSLog(@"string2:%@",[string2 lowercaseString]);//lowercaseString返回转换为小写的字符串
    NSLog(@"string2:%@",[string2 capitalizedString]);//capitalizedString返回每个单词首字母大写的字符串

-----在串中搜索子串 -----

    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);

-----抽取子串 -----

//1、-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);

//2、-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);

//3、-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);

//4、快速枚举

    for(NSString *filename in direnum)    {
        if([[filename pathExtension] isEqualToString:@"jpg"]){
            [files addObject:filename];
        }
    }
    NSLog(@"files:%@",files);

//5、枚举

    NSEnumerator *filenum;
    filenum = [files objectEnumerator];
    while (filename = [filenum nextObject]) {
        NSLog(@"filename:%@",filename);
    }
@"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];   
    NSLog(@"oldArray:%@",oldArray);
    NSEnumerator *enumerator;
    enumerator = [oldArray objectEnumerator];
    id obj;
    while(obj = [enumerator nextObject])    {
        [newArray addObject: obj];
    }
    [newArray sortUsingSelector:@selector(compare:)];
    NSLog(@"newArray:%@", newArray);

-----切分数组-----
//1、从字符串分割到数组－ componentsSeparatedByString:

    NSString *string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];
    NSLog(@"string:%@",string);   
    NSArray *array = [string componentsSeparatedByString:@","];
    NSLog(@"array:%@",array);

//2、从数组合并元素到字符串- componentsJoinedByString:

    NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
    NSString *string = [array componentsJoinedByString:@","];
    NSLog(@"string:%@",string);

-----从目录搜索扩展名为jpg的文件-----

//NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *home;
    home = @"../Users/";
    NSDirectoryEnumerator *direnum;
    direnum = [fileManager enumeratorAtPath: home];
    NSMutableArray *files = [[NSMutableArray alloc] init];
//枚举
    NSString *filename;
    while (filename = [direnum nextObject]) {
        if([[filename pathExtension] hasSuffix:@"jpg"]){
            [files addObject:filename];
        }
    }
//扩展路径 
    NSString *Path = @"~/NSData.txt";
    NSString *absolutePath = [Path stringByExpandingTildeInPath];
    NSLog(@"absolutePath:%@",absolutePath);
    NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
//文件扩展名
    NSString *Path = @"~/NSData.txt";
    NSLog(@"Extension:%@",[Path pathExtension]);

-----查找与替换-----

- (NSString *)stringByReplacingCharactersInRange:(NSRange)range withString:(NSString *)replacement

- (NSString *)stringByReplacingOccurrencesOfString:(NSString *)target withString:(NSString *)replacement

NSMutableString(可修改的字符串)
NSObject -> NSString -> NSMutableString 
Common NSMutableString methods 
+ (id)string; 
- (void)appendString:(NSString *)string; 
- (void)appendFormat:(NSString *)format, ...; 
-----给字符串分配容量-----
    //stringWithCapacity:
    NSMutableString *String;
    String = [NSMutableString stringWithCapacity:40];

-----在已有字符串后面添加字符-----

    //appendString: and appendFormat:
    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);
----- 在已有字符串中按照所给出范围删除字符----   
     //deleteCharactersInRange:
     NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
     [String1 deleteCharactersInRange:NSMakeRange(0, 5)];    // 删除指定范围（location=0，length=5）的字符串
     NSLog(@"String1:%@",String1);
----在已有字符串后面在所指定的位置中插入给出的字符串-----
    //-insertString: atIndex:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 insertString:@"Hi! " atIndex:0];
    NSLog(@"String1:%@",String1);
    [String1 insertString:@"and StringEnd", atIndex:[String1 length]];  //  在可变字符串的最后插入
----将已有的空符串换成其它的字符串-----
    //-setString:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
    [String1 setString:@"Hello Word!"];
    NSLog(@"String1:%@",String1);

----查找-----

   NSRange subRange = [String1 rangeOfString:@"is a"];   // 如果没查找到，则 （subRange.location == NSNotFound）为真。

----按照所给出的范围替换的原有的字符-----

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

----在给定的范围内查找并替换-----

- (NSUInteger)replaceOccurrencesOfString:(NSString *)target withString:(NSString *)replacement options:(NSStringCompareOptions)opts range:(NSRange)searchRange

----判断字符串内是否还包含别的字符串(前缀，后缀)-----
//01： 检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;

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

//02： 查找字符串某处是否包含给定的字符串 - (NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过

NSRange subRange;
subRange = [string1 rangeOfString:@"string A"];  //查找字符串string1中是否包含“string A”。返回NSRange类型。
if(subRange.location == NSNotFound)
     NSLog(@"String not found ");
else  NSLog(@"string is at index %lu, length is %lu", subRange.location, subRange.length);

NSNumber

NSNumber

• (NSNumber *)numberWithInt:(int)value;
• (NSNumber *)numberWithDouble:(double)value;

• (int)intValue;
• (double)doubleValue;

NSNumber可以 将基本数据类型包装起来，形成一个对象，这样就可以给其发送消息，装入NSArray中等等。
NSNumber * intNumber=[NSNumber numberWithInt：100]；
NSNumber *floatNumber=[NSNUmber numberWithFloat:100.00];
int i=[intNumber intValue]；
if([intNumber isEqualToNumber:floatNumber]) ....
NSNumber继承NSObject ，可以使用比较 compare： isEqual等消息

    int i = 1 ;
    long l = 22222;
    NSNumber *number1 = [[NSNumber alloc]initWithInt:i];
    NSLog(@"%@",number1);
    NSNumber *number2 = [[NSNumber alloc]initWithLong:l];
    NSLog(@"%@",number2);
    NSNumber是将基本的类型转换为对象类型
    int  a1 = [number1 intValue];//将NSNumber类型转换成int类型
    NSString *string2 = @"123";
    NSLog(@"%d", [string2 intValue]);将字符串中的数字转换成int类型并输出
    将NSNumber转换成字符串
    [number2  stringValue];
    NSLog(@"%@",[number2  stringValue]);

//    NSMutableString *a = [NSMutableString stringWithString:@"i love you"];
//    NSString *a1 = [a capitalizedString];
//    NSLog(@"%@",a1);
//
    
    
//    NSString *a2 = [NSString stringWithFormat:@"20|[http://www.baidu.com](http://www.baidu.com)"];
//    NSString *a3 = [a2 substringToIndex:2];
//    NSString *a4 = [a2 substringFromIndex:3];
//    NSLog(@"%@\n%@",a3,a4);
    
    
    
//    NSArray *b = [a2 componentsSeparatedByString:@"|"];
//    NSString *c1 = [b objectAtIndex:0];
//    NSString *c2 = [b objectAtIndex:1];
//    NSLog(@"%@   %@",c1,c2);
    
    
    int a = 1 ;
    float b = 2 ;
    BOOL flag = 1 ;
    NSRange c = NSMakeRange(1, 1);
    NSNumber *d1 = [[NSNumber alloc]initWithInt:a];
    NSNumber *d2 = [[NSNumber alloc]initWithFloat:b];
    NSNumber *d3 = [[NSNumber alloc]initWithBool:flag];
    NSValue  *d4 =  [NSValue valueWithRange:c];
    NSMutableArray *aa = [NSMutableArray arrayWithObjects:d1,d2,d3,d4, nil ];
    
    for (int i = 0;i < [aa count];i ++)
    {
        NSLog(@"%@",aa[i]);
        // NSLog(@"%@",[mularr objectAtIndex:i]);

    }