NSSavePanel用AccessoryView更改文件扩展名

Question

我有NSSavePanel和accessoryView，让用户选择图形格式，这样他们就可以将图像(NSImage)保存为文件。到目前为止，我有以下几点。(我跳过了几行以使它更短。)

- (void)exportFile {    
    NSString *filename;
    if (formatIndex1 == 0) { // Default selection by user in Preferences
        filename = @"Untitled.bmp";
    }
    else if (formatIndex1 == 1) {
        filename = @"Untitled.gif";
    }
    ...

    [panel setAllowedFileTypes:[[NSArray alloc] initWithObjects:@"bmp",@"gif",@"jpg",@"jp2",@"png",nil]];
    [panel setAllowsOtherFileTypes:NO];
    [panel setExtensionHidden:NO];
    [panel setCanCreateDirectories:YES];
    [panel setNameFieldStringValue:filename];
    [panel setAccessoryView:accessoryView1];
    [formatMenu1 setAction:@selector(dropMenuChange:)]; // formatMenu1 is NSPopUpButton
    [formatMenu1 setTarget:self];

    [panel beginSheetModalForWindow:window completionHandler:^(NSInteger result) {
        if (result == NSFileHandlingPanelOKButton) {
            // getting panel url
        }
    }];
}

-(void)dropMenuChange:(NSPopUpButton *)sender { 
    NSSavePanel *savePanel = (NSSavePanel *)[sender window];
    [savePanel setNameFieldStringValue:@"..."];
}

我不能百分之百肯定我做得对。我想要实现的是，每当用户在accessoryView的NSPopUpButton上选择文件格式时，我都希望将正确的扩展名附加到当前的文件名。有什么神奇的方法吗？还是我必须以编程的方式将扩展名设置为setNameFieldStringValue的当前文件名？

谢谢你的帮助。

Answer 1

必须使用setNameFieldStringValue设置具有正确扩展名的当前文件名。

-(void)dropMenuChange:(NSPopUpButton *)sender { 
    NSSavePanel *savePanel = (NSSavePanel *)[sender window];
    NSString *nameFieldString = [savePanel nameFieldStringValue];
    NSString *nameFieldStringWithExt = [NSString stringWithFormat:@"%@.%@",[savePanel nameFieldStringValue], popupvalue];
    [savePanel setNameFieldStringValue:nameFieldStringWithExt];
}

Answer 2

我想要实现的是，每当用户在accessoryView的NSPopUpButton上选择文件格式时，我都希望将正确的扩展名附加到当前的文件名。有什么神奇的方法吗？

是的，有。不需要自己用setNameFieldStringValue:来做，让savePanel来做吧。让我们假设fileName是一个像/Users/hg/Pictures/2013/08/Airplanes/pic123.png一样的完整路径，并且它存在一个带有matrix of radio buttons的savePanel的accessoryView。每个按钮都有一个标题，如“jpg”或“png”或.矩阵的作用是-selectFileType:。

- (IBAction) selectFileType:(id)sender
{
    [savePanel setAllowedFileTypes:@[ [[sender selectedCell] title] ] ];
    // this will set the right extension
}

对于使用savePanel，我尝试了以下代码：

- (void) saveImage:(NSImage *) theImg
{
  savePanel = [NSSavePanel savePanel];
  NSString *imageName = [fileName lastPathComponent];
  NSString *suffix = [imageName pathExtension];
  NSString *baseName = [imageName stringByDeletingPathExtension];

  // prepare the savePanel
  [savePanel setAccessoryView:accessoryView];
  [savePanel setAllowedFileTypes:@[ suffix ] ];
  [savePanel setDirectoryURL:[NSURL fileURLWithPath:fileName]];  // convert to URL
  [savePanel setNameFieldStringValue:baseName ];  // without extension !
  // savePanel does append the suffix

  // and now start the savePanel and choose the wanted fileType
  int rtn = [savePanel runModal];   // preferred method since 10.6
  if( rtn==NSFileHandlingPanelCancelButton) return;    // do nothing

  // finally create and save the file
  if( [[[savePanel allowedFileTypes] objectAtIndex:0] isEqualToString:@"jpg" ){
      // save as jpg-file
  }
  // check for other fileTypes
  . . . 
}