Check whether the file exists in iOS development. If the file does not exist, copy it.

First, we will summarize how to obtain the documents directory. In iOS development, we often need to retrieve the complete path of the documents directory for reading and writing files. I have summarized the following two methods:

1. nsstring * documentsdirectory = [nshomedirectory () stringbyappendingpathcomponent: @ "documents"];

2. nsarray * paths = nssearchpathfordirectoriesindomains (nsdocumentdirectory, nsuserdomainmask, yes );

Nsstring * documentsdirectory = [paths objectatindex: 0];

The documentsdirectory above is the complete path of the obtained documents.

 ProgramAll resource files are stored in the package. The method to obtain the package path is as follows:

Nsstring * appdirectory = [[nsbundle mainbundle] bundlepath];

In actual development, we sometimes need to determine whether a resource file under documents exists. If it does not exist, we will copy it from the package. Now we assume that the file to be determined is "xxx.txt ".CodeAs follows:

Nsfilemanager * filemanager = [nsfilemanager defaultmanager];

Nsstring * filepath = [self [documentsdirectory stringbyappendingpathcomponent: @ "xxx.txt"];

If (! [Filemanager fileexistsatpath: filepath]) // if it does not exist

{

Nslog (@ "xxx.txt is not exist ");

Nsstring * datapath = [[[nsbundle mainbundle] bundlepath] stringbyappendingstring: @ "/xxx.txt"]; // obtain the path of the corresponding file in the package

Nserror * error;

If ([filemanager copyitematpath: datapath topath: filepath error: & error]) // copy

{

Nslog (@ "Copy xxx.txt success ");

}

Else

{

Nslog (@ "% @", error );

}

}