源碼地址：前去查看鏈接

/**
 將 UIView 轉換成 UIImage

 @param view 將要轉換的View
 @return 新生成的 UIImage 對象
 */
- (UIImage *)yj_convertCreateImageWithUIView:(UIView *)view{
    
    UIGraphicsBeginImageContext(view.bounds.size);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    [view.layer renderInContext:ctx];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newImage;
}