我使用 NSOpenPanel 允许用户选择一个文件夹来保存文档。我想限制它们可以保存到哪个文件夹(就层次结构而言)。本质上,我想阻止他们选择上面的任何文件夹:
/用户/用户名/
所以文件夹
/用户/用户名/猫/
可以接受,但是
/用户/用户名/
/应用程序/猫/
不会被允许的。我想知道如何实施这个限制。
Thanks.
注意NSOpenPanel http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/NSOpenPanel_Class/Reference/Reference.html继承自NSSavePanel http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/NSSavePanel_Class/Reference/Reference.html,它又定义了一个委托和相应的委托协议NSOpenSavePanelDelegate http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/NSOpenSavePanelDelegate_Protocol/Reference/Reference.html。您可以使用委托来扩展打开面板的行为,以便包含您在问题中列出的限制。
例如,假设应用程序委托实现了打开面板限制,使其符合NSOpenSavePanelDelegate
协议:
@interface AppDelegate : NSObject <NSApplicationDelegate, NSOpenSavePanelDelegate>
@end
在应用程序委托的实现中,告诉打开面板应用程序委托充当打开面板委托:
NSOpenPanel *openPanel = [NSOpenPanel openPanel];
[openPanel setDirectory:NSHomeDirectory()];
[openPanel setCanChooseDirectories:NO];
[openPanel setDelegate:self];
[openPanel runModal];
并实现以下委托方法:
- (BOOL)panel:(id)sender shouldEnableURL:(NSURL *)url {
NSString *path = [url path];
NSString *homeDir = NSHomeDirectory();
return [path hasPrefix:homeDir] && ! [path isEqualToString:homeDir];
}
- (void)panel:(id)sender didChangeToDirectoryURL:(NSURL *)url {
NSString *path = [url path];
NSString *homeDir = NSHomeDirectory();
// If the user has changed to a non home directory, send him back home!
if (! [path hasPrefix:homeDir]) [sender setDirectory:homeDir];
}
- (BOOL)panel:(id)sender validateURL:(NSURL *)url error:(NSError **)outError {
NSString *path = [url path];
NSString *homeDir = NSHomeDirectory();
if (![path hasPrefix:homeDir]) {
if (outError)
*outError = ; // create an appropriate NSError instance
return NO;
}
return YES;
}
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