iOS实现简单长截图

func getImage(in view:UIView?) -> UIImage? {
    guard let view = view else {return nil}
    let size = view.bounds.size
    UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.main.scale)
    view.layer.render(in: UIGraphicsGetCurrentContext()!)
    view.layer.contents = nil
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}

// 先获取状态栏view
func getStatusBar() -> UIView? {
    if Float(UIDevice.current.systemVersion)! >= 13 {
        guard let statusBarManager = UIApplication.shared.keyWindow?.windowscene?.statusBarManager,
              let localStatusBar = statusBarManager.value(forKey: "createLocalStatusBar") as? NSObject,
              let statusBar = localStatusBar.value(forKey: "statusBar") as? UIView else {return nil}
        return statusBar
    } else {
        guard let statusBarWindow = UIApplication.shared.value(forKey: "statusBarWindow") as? UIWindow  else {return nil}
        let statusBar = statusBarWindow.value(forKey: "statusBar") as? UIView
        return statusBar
    }
}

// 再绘制成图片
let statusBarImage = getImage(in: getStatusBar())

if let nav = vc.navigationController { // 表示有导航栏
    let navBar = nav.navigationBar
    let navBarImage = getImage(in: navBar)
}

func getScrollViewImage(scrollView:UIScrollView?) -> UIImage? {
    if let scroll = scrollView {
        let saveOffset = scroll.contentOffset // 保存偏移量，用于绘制图片完成后还原
        let saveFrame = scroll.frame // 保存frame
        scroll.contentOffset = CGPoint.zero
        scroll.frame = CGRect(origin: saveFrame.origin, size: scroll.contentSize) // 设置size和contentSize一致
        
        UIGraphicsBeginImageContext(scroll.frame.size)
        UIGraphicsBeginImageContextWithOptions(CGSize(width: scroll.frame.size.width, height: scroll.frame.size.height), false, UIScreen.main.scale)
        scroll.layer.render(in: UIGraphicsGetCurrentContext()!)
        let scrollImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        scroll.contentOffset = saveOffset // 还原偏移量，否则绘制图片之后，scrollview偏移量不正确
        scroll.frame = saveFrame // 还原frame
        return scrollImage
    }
    return nil
}

func getScrollViewImage(scrollView:UIScrollView?) -> UIImage? {
    if let scroll = scrollView {
        let saveOffset = scroll.contentOffset // 保存偏移量，用于绘制图片完成后还原
        let saveFrame = scroll.frame // 保存frame
        scroll.contentOffset = CGPoint.zero
        scroll.frame = CGRect(origin: saveFrame.origin, size: scroll.contentSize) // 设置size和contentSize一致
        let layouts = scroll.superview!.constraints // 获取的是scrollview的父容器的约束，这才是约束scrollview大小和位置的正确约束
        scroll.superview?.removeConstraints(layouts)
        
        UIGraphicsBeginImageContext(scroll.frame.size)
        UIGraphicsBeginImageContextWithOptions(CGSize(width: scroll.frame.size.width, height: scroll.frame.size.height), false, UIScreen.main.scale)
        scroll.layer.render(in: UIGraphicsGetCurrentContext()!)
        let scrollImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        scroll.contentOffset = saveOffset // 还原偏移量，否则绘制图片之后，scrollview偏移量不正确
        scroll.frame = saveFrame // 还原frame
        scroll.superview?.addConstraints(layouts) // 还原约束
        return scrollImage
    }
    return nil
}

func getScrollViewImage(scrollView:UIScrollView?) -> UIImage? {
    if let scroll = scrollView {
        
        // ......

        let layouts = scroll.superview!.constraints // 获取的是scrollview的父容器的约束，这才是约束scrollview大小和位置的正确约束
        scroll.snp.remakeConstraints { (make) in
            make.top.left.right.equalTo(0)
            make.height.equalTo(scroll.contentSize.height)
        }
        
        // ...... 
        
        scroll.snp.removeConstraints()
        scroll.superview?.addConstraints(layouts) // 还原约束
        
        return scrollImage
    }
    return nil
}

func combineImages(with upImage:UIImage?, and downImage:UIImage?) -> UIImage? {
    if upImage == nil {
        return downImage
    }
    if downImage == nil {
        return upImage
    }
    guard let up = upImage,
          let down = downImage else {return nil}
    let size = CGSize(width: up.size.width, height: up.size.height + down.size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.main.scale)
    
    let upRect = CGRect(origin: CGPoint(x: 0, y: 0), size: up.size)
    up.draw(in: upRect)
    let downRect = CGRect(x: (up.size.width - down.size.width) / 2, y: upRect.origin.y + upRect.size.height, width: down.size.width, height: down.size.height)
    down.draw(in: downRect)
    
    let result = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return result
}