NSSavePanel使用AccessoryView更改文件扩展名

Question

我有NSSavePanel和accessoryView，让用户选择图形格式，以便将图像（NSImage）保存为文件。到目前为止，我有以下内容。（我跳过了一些行以使它变短。）

- (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文件名。有什么神奇的方法吗？或者，我必须为自己以编程方式将当前扩展名正确的文件名设置为setNameFieldStringValue吗？

谢谢你的帮助。

Answer 1

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文件名。有什么神奇的方法吗

是的，确实存在。您不需要自己使用setNameFieldStringValue:，而是让savePanel来执行。让我们假设fileName是像/Users/hg/Pictures/2013/08/Airplanes/pic123.png一样的完整路径，并且它存在一个用于具有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
}

为了使用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
  . . . 
}

Answer 2

您必须使用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];
}