调整icon大小

    CGSize itemSize = CGSizeMake(25, 25);
    UIGraphicsBeginImageContextWithOptions(itemSize, NO, UIScreen.mainScreen.scale);
    CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
    [cell.imageView.image drawInRect:imageRect];
    cell.imageView.image = UIGraphicsGetImageFromCurrentImageContext();