ios 文件操作

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文件操作

在今天的最后一节内容中让我们看一下Foundation中文件操作，下面将以一个例子进行说明：
////  main.m//  FoundationFramework//  Created by fsh on 15/11/12.
//  Copyright © 2015年 fsh. All rights reserved.
//
#import <Foundation/Foundation.h>/*目录操作*/void test1(){    //文件管理器是专门用于文件管理的类    NSFileManager *manager=[NSFileManager defaultManager];        //获得当前程序所在目录(当然可以改变)    NSString *currentPath=[manager currentDirectoryPath];    NSLog(@"current path is :%@",currentPath);    //结果：/Users/kenshincui/Library/Developer/Xcode/DerivedData/FoundationFramework-awxjohcpgsqcpsanqofqogwbqgbx/Build/Products/Debug        //创建目录    NSString *myPath=@"/Users/kenshincui/Desktop/myDocument";    BOOL result= [manager createDirectoryAtPath:myPath withIntermediateDirectories:YES attributes:nil error:nil];    if(result==NO){        NSLog(@"Couldn't create directory!");    }        //目录重命名，如果需要删除目录只要调用removeItemAtPath:<#(NSString *)#> error:<#(NSError **)#>    NSError *error;    NSString *newPath=@"/Users/kenshincui/Desktop/myNewDocument";    if([manager moveItemAtPath:myPath toPath:newPath error:&error]==NO){        NSLog(@"Rename directory failed!Error infomation is:%@",error);    }        //改变当前目录    if([manager changeCurrentDirectoryPath:newPath]==NO){        NSLog(@"Change current directory failed!");    }    NSLog(@"current path is :%@",[manager currentDirectoryPath]);    //结果：current path is :/Users/kenshincui/Desktop/myNewDocument        //遍历整个目录    NSString *path;    NSDirectoryEnumerator *directoryEnumerator= [manager enumeratorAtPath:newPath];    while (path=[directoryEnumerator nextObject]) {        NSLog(@"%@",path);    }    /*结果：     documents     est.txt    */        //或者这样遍历    NSArray *paths= [manager contentsOfDirectoryAtPath:newPath error:nil];    NSObject *p;    for (p in paths) {        NSLog(@"%@",p);    }    /*结果：     documents     est.txt     */}/*文件操作*/void test2(){    NSFileManager *manager=[NSFileManager defaultManager];    NSString *filePath=@"/Users/kenshincui/Desktop/myNewDocument/test.txt";    NSString *filePath2=@"/Users/kenshincui/Desktop/test.txt";    NSString *newPath=@"/Users/kenshincui/Desktop/myNewDocument/test2.txt";        //判断文件是否存在，这个方法也可以判断目录是否存在，这要后面的参数设置位YES    if ([manager fileExistsAtPath:filePath isDirectory:NO]) {        NSLog(@"File exists！");    }        //文件是否可读    if([manager isReadableFileAtPath:filePath]){        NSLog(@"File is readable!");    }        //判断两个文件内容是否相等    if ([manager contentsEqualAtPath:filePath andPath:filePath2]) {        NSLog(@"file1 equals file2");    }        //文件重命名，方法类似于目录重命名    if (![manager moveItemAtPath:filePath toPath:newPath error:nil]) {        NSLog(@"Rename file1 failed!");    }        //文件拷贝    NSString *filePath3=@"/Users/kenshincui/Desktop/test3.txt";    if(![manager copyItemAtPath:newPath toPath:filePath3 error:nil]){        NSLog(@"Copy failed!");    }        //读取文件属性    NSDictionary *attributes;    if ((attributes=[manager attributesOfItemAtPath:newPath error:nil])==nil) {        NSLog(@"Read attributes failed!");    }    for (NSObject *key in attributes) {        NSLog(@"%@=%@",key,attributes[key]);    }    /*结果：         NSFileOwnerAccountID=501         NSFileHFSTypeCode=0         NSFileSystemFileNumber=1781953         NSFileExtensionHidden=0         NSFileSystemNumber=16777218         NSFileSize=27         NSFileGroupOwnerAccountID=20         NSFileOwnerAccountName=kenshincui         NSFileCreationDate=2014-07-28 11:47:58 +0000         NSFilePosixPermissions=420         NSFileHFSCreatorCode=0         NSFileType=NSFileTypeRegular         NSFileExtendedAttributes={         "com.apple.TextEncoding" = <7574662d 383b3133 34323137 393834>;         }         NSFileGroupOwnerAccountName=staff         NSFileReferenceCount=1         NSFileModificationDate=2014-07-28 11:47:58 +0000     */        //删除文件    [manager removeItemAtPath:newPath error:nil];    }//文件操作--文件内容操作（NSData，非结构化字节流对象，有缓冲区管理机制，可用于网络传输）void test3(){    NSFileManager *manager=[NSFileManager defaultManager];    NSString *filePath=@"/Users/kenshincui/Desktop/myNewDocument/test2.txt";    NSData *data=[manager contentsAtPath:filePath];    NSLog(@"%@",data);//存储的是二进制字节流    //结果:<68656c6c 6f20776f 726c642c e4b896e7 958ce4bd a0e5a5bd efbc81>        //NSData转化成字符串    NSString *str1=[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];    NSLog(@"%@",str1);    //结果：hello world,世界你好！        //字符串转化成NSData    NSString *str2=@"Kenshin";    NSData *data2=[str2 dataUsingEncoding:NSUTF8StringEncoding];    NSLog(@"%@",data2);        //当然一般如果仅仅是简单读取文件内容，直接用户NSString方法即可    NSString *content=[NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];    NSLog(@"%@",content);    //结果：hello world,世界你好！    }//文件操作--细粒度控制文件,文件操作柄void test4(){    NSFileManager *manager=[NSFileManager defaultManager];    NSString *filePath=@"/Users/kenshincui/Desktop/myNewDocument/test2.txt";        //以只读方式打开文件    NSFileHandle *fileHandle=[NSFileHandle fileHandleForReadingAtPath:filePath];//注意这个方法返回类型为instancetype，也就是说对于上面的NSFileHandle它的返回类型也是NSFileHandle    NSData *data= [fileHandle readDataToEndOfFile];//完整读取文件    NSString *newPath=@"/Users/kenshincui/Desktop/test4.txt";    [manager createFileAtPath:newPath contents:nil attributes:nil];    NSFileHandle *fileHandle2=[NSFileHandle fileHandleForWritingAtPath:newPath];//以可写方式打开文件    [fileHandle2 writeData:data];//写入文件内容        [fileHandle2 closeFile];//关闭文件        //定位到指定位置,默认在文件开头    [fileHandle seekToFileOffset:12];    NSData *data2= [fileHandle readDataToEndOfFile];    NSLog(@"data2=%@",[[NSString alloc]initWithData:data2 encoding:NSUTF8StringEncoding]);    //结果：data2=世界你好！        [fileHandle seekToFileOffset:6];    NSData *data3=[fileHandle readDataOfLength:5];    NSLog(@"data3=%@",[[NSString alloc]initWithData:data3 encoding:NSUTF8StringEncoding]);    //结果：data3=world        [fileHandle closeFile];    }//文件路径void test5(){    NSString *filePath=@"/Users/kenshincui/Desktop/myDocument";    NSString *filePath2=@"/Users/kenshincui/Desktop/test.txt";    //临时文件所在目录    NSString *path=NSTemporaryDirectory();    NSLog(@"temporary directory is :%@",path);    //结果：/var/folders/h6/lss6gncs509c2pgzgty3wd_40000gn/T/    NSString *lastComponent= [filePath lastPathComponent];    NSLog(@"%@",lastComponent); //结果：myDocument        NSLog(@"%@",[filePath stringByDeletingLastPathComponent]);    //结果：/Users/kenshincui/Desktop    NSLog(@"%@",[filePath stringByAppendingPathComponent:@"Pictrues"]);    //结果：/Users/kenshincui/Desktop/myDocument/Pictrues    NSLog(@"%@",[filePath2 pathExtension]);    //结果：txt        [[filePath pathComponents] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {        NSLog(@"%i=%@",idx,obj);    }];    /*结果：     0=/     1=Users     2=kenshincui     3=Desktop     4=myDocument     */        }//文件操作--NSURLvoid test6(){    NSURL *url=[NSURL URLWithString:@"http://developer.apple.com"];    NSString *str1=[NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];    NSLog(@"%@",str1);}//文件操作--NSBundle，程序包，一般用于获取Resource中的资源（当然由于当前并非IOS应用没有程序包，只是表示当前程序运行路径）//在ios中经常用于读取应用程序中的资源文件，如图片、声音、视频等void test7(){    //在程序包所在目录创建一个文件    NSFileManager *manager=[NSFileManager defaultManager];    NSString *currentPath=[manager currentDirectoryPath];    NSLog(@"current path is :%@",currentPath);    //结果：current path is :/Users/kenshincui/Library/Developer/Xcode/DerivedData/FoundationFramework-awxjohcpgsqcpsanqofqogwbqgbx/Build/Products/Debug    NSString *filePath=[currentPath stringByAppendingPathComponent:@"test.txt"];    [manager createFileAtPath:filePath contents:[@"Hello,world!" dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];            //利用NSBundle在程序包所在目录查找对应的文件    NSBundle *bundle=[NSBundle mainBundle];//主要操作程序包所在目录    //如果有test.txt则返回路径，否则返回nil    NSString *path=[bundle pathForResource:@"test" ofType:@"txt"];//也可以写成：[bundle pathForResource:@"instructions.txt" ofType:nil];    NSLog(@"%@",path);    //结果：/Users/kenshincui/Library/Developer/Xcode/DerivedData/FoundationFramework-awxjohcpgsqcpsanqofqogwbqgbx/Build/Products/Debug/test.txt    NSLog(@"%@",[NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil]);    //结果：Hello,world!        //假设我们在程序运行创建一个Resources目录，并且其中新建pic.jpg，那么用下面的方法获得这个文件完整路径    NSString *path1= [bundle pathForResource:@"pic" ofType:@"jpg" inDirectory:@"Resources"];    NSLog(@"%@",path1);    //结果：/Users/kenshincui/Library/Developer/Xcode/DerivedData/FoundationFramework-awxjohcpgsqcpsanqofqogwbqgbx/Build/Products/Debug/Resources/pic.jpg}int main(int argc,char *argv[]){    test1();    test2();    test3();    test4();    test5();    test6();    test7();        return 0;}
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