iOS開發-文件管理（一）
一、iOS中的沙盒機制
iOS應用程序只能對自己創建的文件系統讀取文件，這個獨立、封閉、安全的空間，叫做沙盒。它一般存放著程序包文件（可執行文件）、圖片、音頻、視頻、plist文件、sqlite數據庫以及其他文件。
每個應用程序都有自己的獨立的存儲空間（沙盒）
一般來說應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
當我們創建應用程序時，在每個沙盒中含有三個文件，分別是Document、Library和temp。
Document：一般需要持久的數據都放在此目錄中，可以在當中添加子文件夾，iTunes備份和恢復的時候，會包括此目錄。
Library：設置程序的默認設置和其他狀態信息
temp：創建臨時文件的目錄，當iOS設備重啟時，文件會被自動清除
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組成部分，結果：（"/","User","apple","testfile.txt"）
-?(NSArray *)pathComponents;
提取路徑的最后一個組成部分，結果：testfile.txt
-?(NSString?*)lastPathComponent;
刪除路徑的最后一個組成部分，結果：/Users/apple
-?(NSString *)stringByDeletingLastPathCpmponent;
將path添加到先郵路徑的末尾，結果：/Users/apple/testfile.txt/app.txt
-?(NSString?*)stringByAppendingPathConmponent:(NSString?*)str;
去路徑最后部分的擴展名，結果：text
-?(NSString?*)pathExtension;
刪除路徑最后部分的擴展名，結果：/Users/apple/testfile
-?(NSString?*)stringByDeletingPathExtension;
路徑最后部分追加擴展名，結果：/User/apple/testfile.txt.jpg
-?(NSString?*)stringByAppendingPathExtension:(NSString?*)str;
三、NSData
NSData是用來包裝數據的
NSData存儲的是二進制數據，屏蔽了數據之間的差異，文本、音頻、圖像等數據都可用NSData來存儲
NSData的用法
1.NSString與NSData互相轉換
NSData－>
NSString
NSString *aString?=?[[NSString alloc]
initWithData:adataencoding:NSUTF8StringEncoding];
NSString－>NSData ???????????????????????????????????????????????????????????????????????????????????? NSString *aString?=?@"1234abcd";
NSData *aData?=?[aString dataUsingEncoding: NSUTF8StringEncoding];
將data類型的數據,轉成UTF8的數據
+(NSString *)dataToUTF8String:(NSData?*)data
{
NSString *buf?=?[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return [buf autorelease];
}
將string轉換為指定編碼
+(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Documents目錄
從Documents目錄讀取數據
在進行網絡數據通信的時候，經常會遇到NSData類型的數據。在該數據是dictionary結構的情況下，系統沒有提供現成的轉換成NSDictionary的方法，為此可以通過Category對NSDictionary進行擴展，以支持從NSData到NSDictionary的轉換。聲明和實現如下：
+?(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
創建一個文件并寫入數據-?(BOOL)createFileAtPath:(NSString *)path contents:(NSData *)data attributes:(NSDictionary *)attr;
從一個文件中讀取數據-?(NSData?*)contentsAtPath:(NSString?*)path;
scrPath路徑上的文件移動到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路徑上的文件復制到dstPath路徑上-?(BOOL)copyItemAtPath:(NSString *)scrPath toPath:(NSString *)dstPath error:(NSError **) error;
比較兩個文件的內容是否一樣-?(BOOL)contentsEqualAtPath:(NSString *)path1 andPath:(NSString *)path2;
文件時候存在-?(BOOL)fileExistsAtPath:(NSString?*)path;
移除文件-?(BOOL)removeItemAtPath:(NSString?*)path error:(NSError **) error;
創建文件管理
NSFileManager
*fileManager?=?[NSFileManager defaultManager];
NSString *path?=?[NSHomeDirectory(?)
stringByAppendingPathComponent:@"holyBible.txt"];
NSString *text?=?@"abcdefg";
將字符串轉成NSData類型NSData *data?=?[text dataUsingEncoding: NSUTF8StringEncoding];
寫入文件BOOL success =?[fileManager createFileAtPath:path contents:data attributes:nil];
創建文件夾
NSString
*filePath?=?[path stringByAppendingPathComponent:@"holyBible.txt"];
NSString
*contect?=?@"abcdefg";
BOOL success =?[fm createFileAtPath:filePath contents:[content
dataUsingEncoding: NSUTF8StringEncoding] attributes:nil];
NSFileManager-讀取內容NSData *fileData?=?[fileManager contentsAtPath:filePath];?????????????????????????????????? NSString *content?=?[[NSString alloc] initWithData:fileData dataUsingEncoding: NSUTF8StringEncoding];
NSData-讀取內容NSString *filePath?=?[path stringByAppendingPathComponent:@"holyBible.txt"];???? NSData *data?=?[NSData dataWithContentOfFile:filePath];
NSString-讀取內容NSString *filePath?=?[path stringByAppendingPathComponent:@"holyBible.txt"];???? NSString *content?=?[[NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
移動、復制文件
移動文件（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);????????????????????????????????????????????????????????????????????????????????????????}
iOS開發-文件管理（二）
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類主要對文件內容進行讀取和寫入操作
NSFileManager類主要對文件的操作（刪除、修改、移動、復制等等）
常用處理方法
+?(id)fileHandleForReadingAtPath:(NSString *)path??打開一個文件準備讀取
+?(id)fileHandleForWritingAtPath:(NSString?*)path??打開一個文件準備寫入
+?(id)fileHandleForUpdatingAtPath:(NSString?*)path??打開一個文件準備更新
-??(NSData?*)availableData;?從設備或通道返回可用的數據
-??(NSData?*)readDataToEndOfFile;?從當前的節點讀取到文件的末尾
-??(NSData?*)readDataOfLength:(NSUInteger)length;?從當前節點開始讀取指定的長度數據
-??(void)writeData:(NSData?*)data;?寫入數據
-??(unsigned long long)offsetInFile;??獲取當前文件的偏移量
-??(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;?將文件的長度設為offset字節
-??(void)closeFile;??關閉文件
向文件追加數據
NSString *homePath??= NSHomeDirectory(?);
NSString *sourcePath?=?[homePath stringByAppendingPathConmpone:@"testfile.text"];
NSFileHandle
*fielHandle?=?[NSFileHandle
fileHandleForUpdatingAtPath:sourcePath];
[fileHandle seekToEndOfFile];??將節點跳到文件的末尾
NSString *str?=?@"追加的數據"
NSData* stringData ?=?[str dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle writeData:stringData];?追加寫入數據
[fileHandle closeFile];
定位數據
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];?獲取數據長度
[fileHandle seekToFileOffset;length/2];?偏移量文件的一半
NSData *data?=?[fileHandle readDataToEndOfFile];
[fileHandle closeFile];
復制文件
NSFileHandle *infile,?*outfile;?輸入文件、輸出文件
NSData?*buffer;?讀取的緩沖數據
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];?創建讀取源路徑文件
if (infile?== nil)
{
return NO;
}
outfile
=?[NSFileHandle
fileHandleForReadingAtPath:outPath];?創建病打開要輸出的文
件
if (outfile?== nil)
{
return NO;
}
[outfile truncateFileAtOffset:0];?將輸出文件的長度設為0
buffer?=?[infile readDataToEndOfFile];??讀取數據
[outfile writeData:buffer];??寫入輸入
[infile closeFile];????????關閉寫入、輸入文件
[outfile closeFile]；
