用法总结：NSNumber、NSString、NSDate、NSCalendarDate、NSData

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 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，用完之后需要手工release
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、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);

[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 a String!"];

NSLog(@"astring:%@",astring);

NSString *path = @"astring.text";

[astring writeToFile: path atomically: YES];

[astring release];

-----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);

[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 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);

[newArray release];

-----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);

[string release];

//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);

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 = [NSCalendarDate calendarDate];

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。

<p style="margin-top: 0px; margin-bottom: 10px; padding-top: 0px; padding-bottom: 0px;"><span class="typ" style="color: rgb(102, 0, 102);">NSData</span><span class="pln"> </span><span class="pun" style="color: rgb(102, 102, 0);">*</span><span class="pln">fileData</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>
<span class="typ" style="color: rgb(102, 0, 102);">NSFileManager</span><span class="pln"> </span><span class="pun" style="color: rgb(102, 102, 0);">*</span><span class="pln">fileManager </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln"> </span><span class="pun" style="color: rgb(102, 102, 0);">[[</span><span class="typ" style="color: rgb(102, 0, 102);">NSFileManager</span><span class="pln"> alloc</span><span class="pun" style="color: rgb(102, 102, 0);">]</span><span class="pln">init</span><span class="pun" style="color: rgb(102, 102, 0);">];</span>
<span class="pln">fileData </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln"> </span><span class="pun" style="color: rgb(102, 102, 0);">[</span><span class="pln">fileManager contentsAtPath</span><span class="pun" style="color: rgb(102, 102, 0);">:</span><span class="pln">path</span><span class="pun" style="color: rgb(102, 102, 0);">];</span><span class="pln">  </span>
<span class="pun" style="color: rgb(102, 102, 0);">[</span><span class="pln">fileManager createFileAtPath</span><span class="pun" style="color: rgb(102, 102, 0);">:</span><span class="pln">path2 contents</span><span class="pun" style="color: rgb(102, 102, 0);">:</span><span class="pln">fileData attributes</span><span class="pun" style="color: rgb(102, 102, 0);">:</span><span class="kwd" style="color: rgb(0, 0, 136);">nil</span><span class="pun" style="color: rgb(102, 102, 0);">];</span><span class="pln">   </span><span class="com" style="color: rgb(136, 0, 0);">//采用默认的属性值</span>
</p>

类型转换 NSData -> NSString：

NSString *strData = [[NSString alloc]initWithData:fileData encoding:NSASCIIStringEncoding];

类型转换 NSString -> NSData：

NSData *fileData2 = [strData dataUsingEncoding:NSUTF8StringEncoding];