起因：

公司项目需要截图，截长图

问题：

如何截图，截长图，网上的资料往往不是太长，就是没解决问题，甚至有不少bug。

解决办法

下面是我找到最精简的方法

1、截图

import UIKit
extension UIView {
    /// 截屏Image
    var captureImage: UIImage? {
        
        // 参数①：截屏区域  参数②：是否透明  参数③：清晰度
        UIGraphicsBeginImageContextWithOptions(frame.size, true, UIScreen.main.scale)
        layer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        
        UIGraphicsEndImageContext()
        return image
    }
}

调用

let image = view.captureImage

2、长图、大图

用上个方法可以截普通的view，但是scrollView，tableView不行，
截长屏需要改变frame的size为contentSize进行截图，操作之后设置回来即可

import UIKit

extension UIScrollView {
    
    /// 截长屏Image
    var captureLongImage: UIImage? {
        
        var image: UIImage? = nil
        let savedContentOffset = contentOffset
        let savedFrame = frame
        
        contentOffset = .zero
        frame = CGRect(x: 0, y: 0,
                       width: contentSize.width,
                       height: contentSize.height)
        
        UIGraphicsBeginImageContext(frame.size)
        UIGraphicsBeginImageContextWithOptions(
            CGSize(width: frame.size.width,
                   height: frame.size.height),
            false,
            UIScreen.main.scale)
        layer.render(in: UIGraphicsGetCurrentContext()!)
        image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        print("contentSize == \(contentSize)")
        contentOffset = savedContentOffset
        frame = savedFrame
        return image
        
    }
}

调用

let longImage = tableView.captureLongImage

保存图片

guard let image = tableView.captureLongImage else {
      return
}
 writeImageToAlbum(image)

fileprivate func writeImageToAlbum(_ image: UIImage) {
        MQProgressHUD.showLoading()
        UIImageWriteToSavedPhotosAlbum(image, self, #selector(image(image:didFinishSavingWithError:contextInfo:)), nil)
}
    
@objc fileprivate func image(image: UIImage, didFinishSavingWithError error: NSError?, contextInfo:UnsafeRawPointer) {
        if let _ = error as NSError? {
            print("保存失败，请重试")
        } else {
            print("保存成功！")
        }
    }
}