NSOpenPanel

NSOpenPanel* panel = [NSOpenPanel openPanel];
[panel setAllowsMultipleSelection:YES];//是否允许多选file
[panel setAllowedFileTypes:@[@"jpg",@"png"]];
//        beginWithCompletionHandler 普通打开
//        beginSheetModalForWindow:completionHandler: sheet模式打开
[panel beginSheetModalForWindow:self.window completionHandler:^(NSInteger result) {
            if (result == NSModalResponseOK) {
            }
}];