//使用一下titleLabel和imageView崇摄，目的是為了準(zhǔn)確的獲取tittle的size
button.titleLabel.backgroundColor = button.backgroundColor;
button.imageView.backgroundColor = button.backgroundColor;
//獲取size （精確的）
CGSize titleSize = button.titleLabel.bounds.size;
CGSize imageSize = button.imageView.bounds.size;
CGFloat interval = 2.0;
//交換圖片和文字的左右位置
button.imageEdgeInsets = UIEdgeInsetsMake(0,titleSize.width + interval, 0, -(titleSize.width + interval));
button.titleEdgeInsets = UIEdgeInsetsMake(0, -(imageSize.width + interval), 0, imageSize.width + interval);
