比较来自NSArray Cocoa的字符串对象后的调用方法

Question

我正在通过此代码选择文件：

- (IBAction)selectFile:(id)sender {

    // Create the File Open Dialog class.
    NSOpenPanel* openDlg = [NSOpenPanel openPanel];

    [openDlg setPrompt:@"Select"];

    fileTypes = [NSArray arrayWithObjects:@"wmv", @"3gp", @"mp4", @"avi", @"mp3", @"mma", @"wav", @"jpeg", @"png", @"jpg", @"tiff", nil];

   // NSArray *JpegfileTypes = [NSArray arrayWithObjects:@"jpeg", @"png", @"jpg", @"tiff", @"mp3" nil];

    // Enable the selection of files in the dialog.
    [openDlg setCanChooseFiles:YES];

    //Enable multiple selection of files
    [openDlg setAllowsMultipleSelection:YES];

    // Enable the selection of directories in the dialog.
    [openDlg setCanChooseDirectories:YES];

    // Display the dialog.  If the OK button was pressed,
    // process the files.
    if ( [openDlg runModalForDirectory:nil file:nil types:fileTypes] == NSOKButton )
    {
        // Get an array containing the full filenames of all
        // files and directories selected.
        files = [[openDlg filenames] retain];

        int i; // Loop counter.
                // Loop through all the files and process them.

        for( i = 0; i < [files count]; i++ )
        {
            NSString *tempFilePath = [files objectAtIndex:i];
            NSLog(@"tempFilePath::: %@",tempFilePath);
            inputFilePath = [[files objectAtIndex:i] retain];
            NSLog(@"filename::: %@", inputFilePath);

            // Do something with the filename.
            [selectedFile setStringValue:inputFilePath];

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

        }

    }

}

然后在选择之后，我已使用此代码来处理所选文件。

- (IBAction)setMessage:(id)sender {

    [fileGenProgress startAnimation:self];

    NSString *message = [[NSString alloc] initWithFormat:@"Started"];
    [lblMessage setStringValue:message];
    [message release];

    [self startProcessingVideoFile];
    [self startProcessingAudioFile];
    [self startProcessingJpg];

}

我面临的问题是，我不明白如何比较不同的字符串，例如所选文件是3gp / mp4还是jpg或mp3。 好像用户选择了一些视频文件，则方法[self startProcessingVideoFile]; 将运行，并且如果他已经选择了一些JPG或PNG等文件，则[self startProcessingAudioFile]; 方法将运行。 如选择的那样，将不仅具有文件扩展名而具有路径。 因此，在这种情况下，如何强制- (IBAction)setMessage:(id)sender方法运行适当的方法。

Answer 1

您可以像这样获取字符串的扩展名（格式）：

NSString *extension = [stringPath pathExtension];

为了进行比较，当您知道文件的扩展名时，这非常容易。 例如：

NSLog(extension);

if ([extension isEqualToString:@"3gp"] || [ext isEqualToString:@"mp4"]) {

    [self startProcessingVideoFile];
}

等等。

更新：

您的IBAction:SetMessage应该如下所示：

- (IBAction)setMessage:(id)sender {

    [fileGenProgress startAnimation:self];

    NSString *message = [[NSString alloc] initWithFormat:@"Started"];
    [lblMessage setStringValue:message];
    [message release];


    NSString *extension = [inputFilePath pathExtension];

    NSLog(extension);

    if ([extension isEqualToString:@"3gp"] || [ext isEqualToString:@"mp4"]) {

        [self startProcessingVideoFile];
    }

    // And etc for others formats.
    //[self startProcessingAudioFile];
    //[self startProcessingJpg];

}