一、iOS中的沙盒機(jī)制
iOS應(yīng)用程序只能對(duì)自己創(chuàng)建的文件系統(tǒng)讀取文件，這個(gè)獨(dú)立、封閉、安全的空間，叫做沙盒。它一般存放著程序包文件（可執(zhí)行文件）、圖片、音頻、視頻、plist文件、sqlite數(shù)據(jù)庫以及其他文件。
每個(gè)應(yīng)用程序都有自己的獨(dú)立的存儲(chǔ)空間（沙盒）
一般來說應(yīng)用程序之間是不可以互相訪問
模擬器沙盒的位置
/User/userName/Library/Application Support/iPhone Simulator
當(dāng)我們創(chuàng)建應(yīng)用程序時(shí)，在每個(gè)沙盒中含有三個(gè)文件，分別是Document、Library和temp。
Document：一般需要持久的數(shù)據(jù)都放在此目錄中，可以在當(dāng)中添加子文件夾，iTunes備份和恢復(fù)的時(shí)候，會(huì)包括此目錄。
Library：設(shè)置程序的默認(rèn)設(shè)置和其他狀態(tài)信息
temp：創(chuàng)建臨時(shí)文件的目錄，當(dāng)iOS設(shè)備重啟時(shí)，文件會(huì)被自動(dòng)清除
獲取沙盒目錄
獲取程序的根目錄（home）目錄
NSString *homePath?= NSHomeDirectory()
獲取Document目錄
NSArray ?*paths?= NSSearchPathDorDirectoriesInDomains(NSDocumentDicrectory,, NSUserDomainMark, YES);?????????????????????????????????????????????????????????????????????????? NSString *docPath?=?[paths lastObject];
獲取Library目錄
NSArray *paths?= NSSearchPathForDirectoriseInDomains(NSLibraryDirectory, NSUserDomainMask, YES);?????????????????????????????????????????????????????????????????????????????????? NSString *docPath?=?[paths lastObject];
獲取Library中的Cache
NSArray *paths?= NSSearchPathForDirectoriseInDomains(NSCachesDirectory, NSUserDomainMask, YES);?????????????????????????????????????????????????????????????????????????????????? NSString *docPath?=?[paths lastObject];
獲取temp路徑
NSString *temp?= NSTemporaryDirectory(?);
二、NSString類路徑的處理方法
文件路徑的處理
NSString *path?=?@"/Uesrs/apple/testfile.txt"
常用方法如下
獲得組成此路徑的各個(gè)組成部分，結(jié)果：（"/","User","apple","testfile.txt"）
-?(NSArray *)pathComponents;
提取路徑的最后一個(gè)組成部分，結(jié)果：testfile.txt
-?(NSString?*)lastPathComponent;
刪除路徑的最后一個(gè)組成部分，結(jié)果：/Users/apple
-?(NSString *)stringByDeletingLastPathCpmponent;
將path添加到先郵路徑的末尾，結(jié)果：/Users/apple/testfile.txt/app.txt
-?(NSString?*)stringByAppendingPathConmponent:(NSString?*)str;
去路徑最后部分的擴(kuò)展名，結(jié)果：text
-?(NSString?*)pathExtension;
刪除路徑最后部分的擴(kuò)展名，結(jié)果：/Users/apple/testfile
-?(NSString?*)stringByDeletingPathExtension;
路徑最后部分追加擴(kuò)展名，結(jié)果：/User/apple/testfile.txt.jpg
-?(NSString?*)stringByAppendingPathExtension:(NSString?*)str;
三、NSData
NSData是用來包裝數(shù)據(jù)的
NSData存儲(chǔ)的是二進(jìn)制數(shù)據(jù)，屏蔽了數(shù)據(jù)之間的差異，文本、音頻、圖像等數(shù)據(jù)都可用NSData來存儲(chǔ)
NSData的用法
1.NSString與NSData互相轉(zhuǎn)換
NSData－> NSString ??????????????????????????????????????????????????????????????????????????????????? NSString *aString?=?[[NSString alloc] initWithData:adataencoding:NSUTF8StringEncoding];
NSString－>NSData ???????????????????????????????????????????????????????????????????????????????????? NSString *aString?=?@"1234abcd";
NSData *aData?=?[aString dataUsingEncoding: NSUTF8StringEncoding];
將data類型的數(shù)據(jù),轉(zhuǎn)成UTF8的數(shù)據(jù)
+(NSString *)dataToUTF8String:(NSData?*)data
{
NSString *buf?=?[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return [buf autorelease];
}
將string轉(zhuǎn)換為指定編碼
+(NSString *)changeDataToEncodinString:(NSData?*)data encodin:(NSStringEncoding )encodin{
NSString *buf?=?[[[NSString alloc] initWithData:data encoding:encodin] autorelease];
return buf;
}
2. NSData 與 UIImage
NSData－>UIImage
UIImage *aimage?=?[UIImage imageWithData: imageData];
//例：從本地文件沙盒中取圖片并轉(zhuǎn)換為NSData
NSString *path?=?[[NSBundle mainBundle] bundlePath];
NSString *name?=?[NSString stringWithFormat:@"ceshi.png"];
NSString *finalPath?=?[path stringByAppendingPathComponent:name];
NSData *imageData?=?[NSData dataWithContentsOfFile: finalPath];
UIImage *aimage?=?[UIImage imageWithData: imageData];
3.NSData與NSArray? NSDictionary
+(NSString *)getLocalFilePath:(NSString?*) fileName
{
return [NSString stringWithFormat:@"%@/%@%@", NSHomeDirectory(),@“Documents”,fileName];
}
包括將NSData寫進(jìn)Documents目錄
從Documents目錄讀取數(shù)據(jù)
在進(jìn)行網(wǎng)絡(luò)數(shù)據(jù)通信的時(shí)候，經(jīng)常會(huì)遇到NSData類型的數(shù)據(jù)。在該數(shù)據(jù)是dictionary結(jié)構(gòu)的情況下，系統(tǒng)沒有提供現(xiàn)成的轉(zhuǎn)換成NSDictionary的方法，為此可以通過Category對(duì)NSDictionary進(jìn)行擴(kuò)展，以支持從NSData到NSDictionary的轉(zhuǎn)換。聲明和實(shí)現(xiàn)如下：
+?(NSDictionary *)dictionaryWithContentsOfData:(NSData?*)data?{
CFPropertyListRef list = CFPropertyListCreateFromXMLData(kCFAllocatorDefault,?(CFDataRef)data, kCFPropertyListImmutable, NULL);
if(list == nil) return nil;
if ([(id)list isKindOfClass:[NSDictionary class]])?{
return [(NSDictionary?*)list autorelease];
}
else {
CFRelease(list);
return nil;
}
}
四、文件管理常用方法
NSFileManager
創(chuàng)建一個(gè)文件并寫入數(shù)據(jù)-?(BOOL)createFileAtPath:(NSString *)path contents:(NSData *)data attributes:(NSDictionary *)attr;
從一個(gè)文件中讀取數(shù)據(jù)-?(NSData?*)contentsAtPath:(NSString?*)path;
scrPath路徑上的文件移動(dòng)到dstPath路徑上，注意這里的路徑是文件路徑而不是目錄-?(BOOL)moveItemAtPath:(NSString?*)srcPath toPath:(NSString *)dstPath error:(NSError **) error;
scrPath路徑上的文件復(fù)制到dstPath路徑上-?(BOOL)copyItemAtPath:(NSString *)scrPath toPath:(NSString *)dstPath error:(NSError **) error;
比較兩個(gè)文件的內(nèi)容是否一樣-?(BOOL)contentsEqualAtPath:(NSString *)path1 andPath:(NSString *)path2;
文件時(shí)候存在-?(BOOL)fileExistsAtPath:(NSString?*)path;
移除文件-?(BOOL)removeItemAtPath:(NSString?*)path error:(NSError **) error;
創(chuàng)建文件管理
NSFileManager *fileManager?=?[NSFileManager defaultManager];????????????????????????? NSString *path?=?[NSHomeDirectory(?)? stringByAppendingPathComponent:@"holyBible.txt"];???????????????????????????????????????????????????????????????????????????????????????????????????? NSString *text?=?@"abcdefg";
將字符串轉(zhuǎn)成NSData類型NSData *data?=?[text dataUsingEncoding: NSUTF8StringEncoding];
寫入文件BOOL success =?[fileManager createFileAtPath:path contents:data attributes:nil];
創(chuàng)建文件夾
NSString *filePath?=?[path stringByAppendingPathComponent:@"holyBible.txt"];???? NSString *contect?=?@"abcdefg";???????????????????????????????????????????????????????????????????? BOOL success =?[fm createFileAtPath:filePath contents:[content dataUsingEncoding: NSUTF8StringEncoding] attributes:nil];
NSFileManager-讀取內(nèi)容NSData *fileData?=?[fileManager contentsAtPath:filePath];?????????????????????????????????? NSString *content?=?[[NSString alloc] initWithData:fileData dataUsingEncoding: NSUTF8StringEncoding];
NSData-讀取內(nèi)容NSString *filePath?=?[path stringByAppendingPathComponent:@"holyBible.txt"];???? NSData *data?=?[NSData dataWithContentOfFile:filePath];
NSString-讀取內(nèi)容NSString *filePath?=?[path stringByAppendingPathComponent:@"holyBible.txt"];???? NSString *content?=?[[NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
移動(dòng)、復(fù)制文件
移動(dòng)文件（重命名）NSString *toPath?=?[NSHomeDirectory(?) stringByAppendingPathComponent:@"hellogod/New Testament.txt"];??????????????????????????????????????????????????????????????????????????????[fm createDirectoryAtPath:[toPath stringByDeletingLastPathComponent] withIntermediateDirectories:YES attributes:nil error:nil];?????????????????????????????????????????????????? NSError *error;???????????????????????????????????????????????????????????????????????????????????????????? BOOL isSuccess =?[fm moveItemAtPath:filePath toPath:toPath error:&error];
復(fù)制文件（重命名）NSString *copyPath?=?[NSHomeDirectory(?) stringByAppendingPathComponent:@"備份/Old Testament.txt"];[fm createDirectoryAtPath:[toPath stringByDeletingLastPathComponent] withIntermediateDirectories:YES attributes:nil error:nil];?????????????????????????????????????????????????? BOOL success =?[fm copyItemAtPath:toPath toPath:toPath error:nil];
刪除文件、獲取文件大小
判斷文件是否存在和刪除文件if([fm fileExistsAtPath])?????????????????????????????????????????????????????????????????????????????????????{??????????????????????????????????????????????????????????????????????????????????????????????????????????????????? if ([fm removeItemAtPath:copyPath])????????????????????????????????????????????????????????????????{?????????????????????????????????????????????????????????????????????????????????????????????????????????????????? NSLog(@"remove success");????????????????????????????????????????????????????????????????????????????}??????????????????????????????????????????????????????????????????????????????????????????????????????????????????}
獲取文件大小NSFileManager *fileManager?=?[NSFileManager defaultManager];?????????????????????????獲得文件的屬性字典???????????????????????????????????????????????????????????????????????????????????????? NSDictionary *attrDic?=?[fileManager attributesOfItemAtpath:sourcePath error:nil];? NSNumber *fileSize?=?[attrDic objectForKey:NSFileSize];
獲取目錄文件信息NSFileManager *fileManager?=?[NSFileManager defaultManager];???????????????????????? NSString *enuPath?=?[NSHomeDirectoty(?) stringByAppendingPathComponent:@"Test"];?????????????????????????????????????????????????????????????????????????????????????????????????????????? NSDictionaryEnumerator *dirEnum?=?[fileManager enumeratorAtPath:enuPath];???? NSString *path?= nil;????????????????????????????????????????????????????????????????????????????????????? while ((path?=?[dirEnum nextObject]}?!= nil)????????????????????????????????????????????????????????{????????????????????????????????????????????????????????????????????????????????????????????????????????????????? NSLog(@"%@",path);
五、Plist文件
String方式添加
NSString *path?=?[NSHomeDirectory(?)? stringByAppendingPathComponent:@"Array.plist"];
NSString *content?=?@"abcd";
[contect writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];
Array方式添加
NSString *path?=?[NSHomeDirectory(?)? stringByAppendingPathComponent:@"Array.plist"];
[NSArray *array?=?[[NSArray alloc] initWithObjects:@"123",?@"798"，@"000",nil];???????[array writeToFile:path atomically:YES];
Dictionary方式添加
NSString *path?=?[NSHomeDirectory(?)? stringByAppendingPathComponent:@"Dic.plist"];
NSDictionary *dic?=?[NSDictionary alloc] initWithObjects:@"first",@"second",@"third"forKeys:@"123",@"456",@"798"];???????????????????????????????????????????????????????????????????????[dic writeToFile:path atomically:YES];
數(shù)組、字典只能將BOOL、NSNumber、NSString、NSData、NSDate、NSArray、NSDictionary寫入屬性列表plist文件
六、讀取文件類和常用方法
NSFileHandle類主要對(duì)文件內(nèi)容進(jìn)行讀取和寫入操作
NSFileManager類主要對(duì)文件的操作（刪除、修改、移動(dòng)、復(fù)制等等）
常用處理方法
+?(id)fileHandleForReadingAtPath:(NSString *)path??打開一個(gè)文件準(zhǔn)備讀取
+?(id)fileHandleForWritingAtPath:(NSString?*)path??打開一個(gè)文件準(zhǔn)備寫入
+?(id)fileHandleForUpdatingAtPath:(NSString?*)path??打開一個(gè)文件準(zhǔn)備更新
-??(NSData?*)availableData;?從設(shè)備或通道返回可用的數(shù)據(jù)
-??(NSData?*)readDataToEndOfFile;?從當(dāng)前的節(jié)點(diǎn)讀取到文件的末尾
-??(NSData?*)readDataOfLength:(NSUInteger)length;?從當(dāng)前節(jié)點(diǎn)開始讀取指定的長(zhǎng)度數(shù)據(jù)
-??(void)writeData:(NSData?*)data;?寫入數(shù)據(jù)
-??(unsigned long long)offsetInFile;??獲取當(dāng)前文件的偏移量
-??(void)seekToFileOffset:(unsigned long long)offset;?跳到指定文件的偏移量
-??(unsigned long long)seekToEndOfFile;?跳到文件末尾
-??(void)truncateFileAtOffset:(unsigned long long)offset;?將文件的長(zhǎng)度設(shè)為offset字節(jié)
-??(void)closeFile;??關(guān)閉文件
向文件追加數(shù)據(jù)
NSString *homePath??= NSHomeDirectory(?);
NSString *sourcePath?=?[homePath stringByAppendingPathConmpone:@"testfile.text"];
NSFileHandle *fielHandle?=?[NSFileHandle fileHandleForUpdatingAtPath:sourcePath];
[fileHandle seekToEndOfFile];??將節(jié)點(diǎn)跳到文件的末尾
NSString *str?=?@"追加的數(shù)據(jù)"
NSData* stringData ?=?[str dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle writeData:stringData];?追加寫入數(shù)據(jù)
[fileHandle closeFile];
定位數(shù)據(jù)
NSFileManager *fm?=?[NSFileManager defaultManager];
NSString *content?=?@"abcdef";
[fm createFileAtPath:path contents:[content dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];
NSFileHandle *fileHandle?=?[NSFileHandle fileHandleForReadingAtPath:path];
NSUInteger length =?[fileHandle availabelData] length];?獲取數(shù)據(jù)長(zhǎng)度
[fileHandle seekToFileOffset;length/2];?偏移量文件的一半
NSData *data?=?[fileHandle readDataToEndOfFile];
[fileHandle closeFile];
復(fù)制文件
NSFileHandle *infile,?*outfile;?輸入文件、輸出文件
NSData?*buffer;?讀取的緩沖數(shù)據(jù)
NSFileManager?*fileManager?=?[NSFileManager defaultManager];
NSString *homePath?= NSHomeDirectory(?);
NSString *sourcePath?=?[homePath stringByAppendingPathComponent:@"testfile.txt"];??源文件路徑
NSString *outPath?=?[homePath stringByAppendingPathComponent:@"outfile.txt"];?輸出文件路徑
BOOL sucess ?=?[fileManager createFileAtPath:outPath contents:nil attributes:nil];
if (!success)
{
return N0;
}
infile =?[NSFileHandle fileHandleForReadingAtPath:sourcePath];?創(chuàng)建讀取源路徑文件
if (infile?== nil)
{
return NO;
}
outfile =?[NSFileHandle fileHandleForReadingAtPath:outPath];?創(chuàng)建病打開要輸出的文件
if (outfile?== nil)
{
return NO;
}
[outfile truncateFileAtOffset:0];?將輸出文件的長(zhǎng)度設(shè)為0
buffer?=?[infile readDataToEndOfFile];??讀取數(shù)據(jù)
[outfile writeData:buffer];??寫入輸入
[infile closeFile];????????關(guān)閉寫入、輸入文件
[outfile closeFile]；
轉(zhuǎn)自Seven的技術(shù)博客 http://seven-sally.lofter.com/，侵刪。
