PowerShell script to download hi-res photos from Apple iCloud sharedalbum

download-icloud-sharedalbum.ps1

# PowerShell script to download hi-res photos from
# Apple iCloud sharedalbum
#
# The script saves jsons and txt to its directory for debug reasons
# Please remove them manually later



$target_url = "https://www.icloud.com/sharedalbum/#B1e5ZhN2vMlt0Z"




# Required function to split the large arrays to chunks
function Create-Batch {
    [CmdletBinding()]
    param (
        [Int]$Size,
        [Parameter(Mandatory=$true, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]$InputObject
    )
    begin {
        $Batch = [Collections.Generic.List[object]]::new()
    }
    process {
        if ($Size -and $Batch.get_Count() -ge $Size) {
            ,$Batch
            $Batch = [Collections.Generic.List[object]]::new()
        }
        $Batch.Add($_)
    }
    End {
        if ($Batch.get_Count()) { , $Batch }
    }
}

# script begin
$folder_id = $target_url.Substring($target_url.IndexOf("#") + 1)   

# First make a fake request and get a valid download host
$webstream_default_url = "https://sharedstreams.icloud.com/$($folder_id)/sharedstreams/webstream" 
try {
    Invoke-RestMethod -Uri $webstream_default_url -Method 'Post' -Body '{"streamCtag":null}'
} catch {
    # if http code was 330 redirect, we lookup take valid host id from response
    if ($_.Exception.Response.StatusCode.value__ -eq 330) {
        if($_.ErrorDetails.Message -match 'X-Apple-MMe-Host":"(.+)"') {
           $url_host = $Matches[1]
           Write-Output "Received server name: $($url_host)"
        }
    } else {
        $_.Exception.Response
        exit
    }
}

# generate download urls and filename for jsons
# i download jsons to files first for debug purposes 
$webstream_url = "https://$($url_host)/$($folder_id)/sharedstreams/webstream" 
$webstream_file = "$($PSScriptRoot)\webstream.json"
$webassets_url = "https://$($url_host)/$($folder_id)/sharedstreams/webasseturls" 
$webassets_file = "$($PSScriptRoot)\webasseturls.json"

# download webstream_url if not before
# webstream_url is main jsons with all photos data
if(!(Test-Path $webstream_file -PathType Leaf)) {
    Write-Output "Get $($webstream_url)"    
    Write-Output "Json save to $($webstream_file)"
    Invoke-RestMethod -Uri $webstream_url -Method 'Post' -Body '{"streamCtag":null}' -OutFile $webstream_file
}

# read downloaded file to json
Write-Output "Json load $($webstream_file)"
$webstream_obj = Get-Content $webstream_file | ConvertFrom-Json
Write-Output "Total photos: $($webstream_obj.photos.Count)" 

# Iterate through all photos in batches
# for debug needs you may want tos limit to -First x objects 
$webstream_obj.photos | Select-Object -First 5000 | Create-Batch -Size 500 | ForEach-Object {
    Write-Output "Process batch of: $($_.Count)" 

    # We download list if all urls for current photoGuids batch 
    # First, create request body, as /webassets expects POST request with body like 
    # {"photoGuids":["...", "..."]}
    $body =  @{ photoGuids = $_ | Select -ExpandProperty photoGuid } | ConvertTo-Json
    
    # download the list
    # webassets Response contains all available photo sizes for current batch, and we may want to filter it further
    Invoke-RestMethod -Uri $webassets_url -Method 'Post' -Body $body -OutFile $webassets_file
    $webassets_obj = Get-Content $webassets_file | ConvertFrom-Json
    Write-Output "Assets for this batch found: $($webassets_obj.items.psobject.Properties.Value.Count)"

    # Filter files to download.
    # Iterate current batch and collect only largest files per each photoGuid 
    # You may want to skip this block to download all available photo sizes
    $largest_checksums = @()
    $_ | ForEach-Object {
        $largest_file = $_.derivatives.PSObject.Properties | Select-Object -ExpandProperty Value | Sort-Object {[int]$_.filesize} -Descending | Select-Object -First 1
        $largest_checksums += $largest_file.checksum
    }
    # Write-Output "Hi-res files: $($largest_checksums.Count)"

    $i=0
    $webassets_obj.items.PSObject.Properties | ForEach-Object {
        Write-Output "File $($_.Name)"
        # comment this out, if you want to download all available sizes
        if ($largest_checksums -NotContains $_.Name.ToString()) {
            Write-Output "Low res skip"
            return
        }
        $url = (-join("https://", $_.Value.url_location,  $_.Value.url_path))

        # dump url to file
        $url | Out-File -FilePath "$($PSScriptRoot)\urls.txt" -Append 

        Write-Output "Download"
        # download file with headers
        $Response = Invoke-WebRequest $Url
        
        # extract original file name
        $ContentDisposition = $Response.Headers.'Content-Disposition'
        $i1 = $ContentDisposition.IndexOf('filename="')+10
        $i2 = $ContentDisposition.IndexOf('"', $i1)
        $FileName = $ContentDisposition.Substring($i1, $i2-$i1)
        $FilePath = "$($PSScriptRoot)\$($FileName)"

        # save and cleanup
        [IO.File]::WriteAllBytes($FilePath, $Response.Content)
        Remove-Variable Response -Force
        [GC]::Collect()

        Write-Output "Saved: $($FileName)"
    }
}

I think you should put a placeholder for the base link, its still using your shared album. In case you dont want your album to be available for everyone