#define kKeyWindow [UIApplication sharedApplication].keyWindow

UIGraphicsBeginImageContext(kKeyWindow.bounds.size);

    [kKeyWindow.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    NSData *dataImage = UIImageJPEGRepresentation(image, 0.5);

    UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);

    BOOL iss = [dataImage writeToFile:@"/Users/apple/Desktop/未命名文件夹/i.png" atomically:YES];