用法总结：NSNumber、NSString、NSData

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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

NSString

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 aString!";

//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，用完之后需要手工release

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

//3、在以上方法中，提升速度:initWithString方法

NSString*astring = [[NSString alloc] initWithString:@"Thisis a String!"];
NSLog(@"astring:%@",astring);
[astring release];
//4、创建临时字符串

NSString*astring;
astring =[NSString stringWithCString:"This is atemporary string"];
NSLog(@"astring:%@",astring);

// OR

NSString* scriptString =[NSString stringWithString:@" tellapplication "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.Thisis %i string!",i,j]];
NSLog(@"astring:%@",astring);
[astring release];

-----从文件读取字符串-----
NSString*path = @"astring.text";
NSString *astring =[[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];

-----写字符串到文件----
    NSString*astring = [[NSString alloc] initWithString:@"This is aString!"];
NSLog(@"astring:%@",astring);
NSString *path =@"astring.text";
[astring writeToFile: path atomically:YES];
[astringrelease];
-----比较两个字符串-----
//1、用C比较:strcmp函数
    charstring1[] = "string!";
char string2[] ="string!";
if(strcmp(string1, string2) = =0)
{
     NSLog(@"1");
}
//2、isEqualToString方法
NSString *astring01 = @"Thisis a String!";
NSString *astring02 = @"Thisis 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 = @"Thisis a String!";
NSString *astring02 = @"Thisis 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 = @"thisis 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 aString!";
NSString *astring02 = @"Thisis 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 = @"thisis a String!";
NSString *astring02 = @"Thisis 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 = @"thisis a String!";
NSString *astring02 = @"Thisis a String!";
BOOL result = [astring01compare: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:%@",[string1uppercaseString]);//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 = [string1rangeOfString:string2];
int location =range.location;
int leight =range.length;
NSString *astring =[[NSString alloc] initWithString:[NSStringstringWithFormat:@"Location:%i,Leight:%i",location,leight]];
NSLog(@"astring:%@",astring);
[astring release];

-----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 isa 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 isa 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 isa string";
NSString *string2 =[string1 substringWithRange:NSMakeRange(0,4)];
NSLog(@"string2:%@",string2);

//4、快速枚举
    for(NSString*filename indirenum)   {
       if([[filename pathExtension] isEqualToString:@"jpg"]){
            [filesaddObject:filename];
       }
   }
  NSLog(@"files:%@",files);

//5、枚举
NSEnumerator *filenum;
filenum = [filesobjectEnumerator];
while (filename = [filenumnextObject]) {
NSLog(@"filename:%@",filename);
}

@"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];
NSLog(@"oldArray:%@",oldArray);
NSEnumerator*enumerator;
enumerator = [oldArrayobjectEnumerator];
id obj;
while(obj = [enumeratornextObject])   {
     [newArrayaddObject: obj];
}
[newArraysortUsingSelector:@selector(compare:)];
NSLog(@"newArray:%@",newArray);
[newArrayrelease];

-----切分数组-----
//1、从字符串分割到数组－componentsSeparatedByString:
NSString *string = [[NSStringalloc] initWithString:@"One,Two,Three,Four"];
NSLog(@"string:%@",string);
NSArray *array= [string componentsSeparatedByString:@","];
NSLog(@"array:%@",array);
[stringrelease];

//2、从数组合并元素到字符串-componentsJoinedByString:
NSArray *array = [[NSArrayalloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSString *string = [arraycomponentsJoinedByString:@","];
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 = [fileManagerenumeratorAtPath: home];
    NSMutableArray*files = [[NSMutableArray alloc]init];
//枚举
NSString *filename;
while (filename = [direnumnextObject]) {
     if([[filenamepathExtension] hasSuffix:@"jpg"]){
       [filesaddObject:filename];
     }
}
//扩展路径
   NSString *Path = @"~/NSData.txt";
NSString *absolutePath =[Path stringByExpandingTildeInPath];
NSLog(@"absolutePath:%@",absolutePath);
NSLog(@"Path:%@",[absolutePathstringByAbbreviatingWithTildeInPath]);
//文件扩展名
NSString *Path =@"~/NSData.txt";
NSLog(@"Extension:%@",[PathpathExtension]);

-----查找与替换-----

- (NSString *)stringByReplacingCharactersInRange:(NSRange)rangewithString:(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 = [NSMutableStringstringWithCapacity:40];

-----在已有字符串后面添加字符-----

    //appendString:and appendFormat:
    NSMutableString*String1 = [[NSMutableString alloc] initWithString:@"This is aNSMutableString"];
//[String1 appendString:@", I will be addingsome character"];
[String1 appendFormat:[NSStringstringWithFormat:@", 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 aNSMutableString"];
    [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 aNSMutableString"];
[String1 insertString:@"Hi! "atIndex:0];
NSLog(@"String1:%@",String1);
    [String1insertString:@"and StringEnd", atIndex:[String1length]]; // 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 aNSMutableString"];
[String1 setString:@"Hello Word!"];
NSLog(@"String1:%@",String1);

----查找-----
NSRange subRange =[String1 rangeOfString:@"isa"]; // 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 aNSMutableString"];
[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";
[String1hasPrefix:@"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:@"stringA"]; //查找字符串string1中是否包含“stringA”。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);

NSDate

NSCalendarDate

NSCalendarDate对象包含了日期和时间、时区以及一个带有格式的字符串，它从NSDate继承而来。

NSCalendarDate对象是immutable的，一旦被创建，无法修改其中的时间和日期，当然可以修改那个带格式的字符串和时区。

以下是常用方法：

+(id)calendarDate; //创建当前日期和时间以及默认格式的NSCalendarDate对象，时区为机器设置好的时区。

+(id)dateWithYear:(int)year

month:(unsigned)month

day:(unsigned)day

hour:(unsigned)hour

minute:(unsigned)minute

second:(unsigned)second

timeZone:(NSTimeZone *)aTimeZone

-(int)dayOfCommonEra; //得到从公元1年算起，有多少天

-(int)dayOfMonth; //返回是月的第几天（1-31）

-(int)dayOfWeek; //返回是周的第几天（0-6）

-(int)dayOfYear; //返回是年的第几天（1-366）

-(int)hourOfDay; // 返回是日的第几个小时（0-23）

-(void)setCalendarFormate:(NSString*)format

--------创建NSCalendarDate对象--------

NSCalendarDate*now;

now = [NSCalendarDatecalendarDate];

NSTimeZone *pacific =[NSTimeZone timeZoneWithName:@"PST"];

NSCalendarDate *hotTime= [NSCalendarDate dateWithYear:2011 month:2 day:3 hour:14 minute:0 second:0 timeZone:pacific];

NSData

使用文件时，需要频繁地将数据读入一个临时存储区，它通常成为缓冲区。

NSData类提供了一种简单的方式，它用来设置缓冲区、将文件的内容读入缓冲区，或将缓冲区的内容写到一个文件。

对于32位应用程序，NSDATA缓存区最多可以存储2GB的数据。

我们既可定义不变缓冲区（NSData类），也可定义可变的缓冲区（NSMutableData类）。

下面代码展示了如何将文件的内容读入内存缓冲区，然后再将缓冲区的内容写入到另一个文件中。

<span style="color:#66066;">NSData</span><span> </span><span style="color:#66660;">*</span><span>fileData</span><span style="color:#66660;">;</span><span style="color:#66066;">NSFileManager</span><span> </span><span style="color:#66660;">*</span><span>fileManager </span><span style="color:#66660;">=</span><span> </span><span style="color:#66660;">[[</span><span style="color:#66066;">NSFileManager</span><span> alloc</span><span style="color:#66660;">]</span><span>init</span><span style="color:#66660;">];</span><span>fileData </span><span style="color:#66660;">=</span><span> </span><span style="color:#66660;">[</span><span>fileManager contentsAtPath</span><span style="color:#66660;">:</span><span>path</span><span style="color:#66660;">];</span><span>  </span><span style="color:#66660;">[</span><span>fileManager createFileAtPath</span><span style="color:#66660;">:</span><span>path2 contents</span><span style="color:#66660;">:</span><span>fileData attributes</span><span style="color:#66660;">:</span><span style="color:#0088;">nil</span><span style="color:#66660;">];</span><span>   </span><span style="color:#8800;">//采用默认的属性值</span>

类型转换 NSData -> NSString：

NSString *strData =[[NSString alloc]initWithData:fileDataencoding:NSASCIIStringEncoding];

类型转换 NSString-> NSData：

NSData *fileData2 = [strDatadataUsingEncoding:NSUTF8StringEncoding];

NSMutableData

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