OS X 开发：打开文件面板NSOpenPanel应用

    NSOpenPanel * panel = [NSOpenPanel openPanel];
    //设置是否解析别名
    panel.resolvesAliases = NO;
    //设置是否允许选择文件夹
    panel.canChooseDirectories = YES;
    //设置是否允许选择文件
    panel.canChooseFiles = YES;
    //设置是否允许多选
    panel.allowsMultipleSelection = YES;
    NSInteger result = [panel runModal];
    if (result==NSFileHandlingPanelOKButton) {
        NSLog(@"%@",panel.URLs);
    }

enum {
    NSFileHandlingPanelCancelButton	= NSModalResponseCancel,//用户点击了取消按钮
    NSFileHandlingPanelOKButton	= NSModalResponseOK,//用户点击了OK按钮
};