Load map and take the screenshot was very memory management thing and very difficult to manage it. so Is there any way to get the screenshot of the map from URL with custom marker?
Do you mean getting thumbnail of a webMap for which you have an URL in this format: http://www.arcgis.com/home/item.html?id=8bf7167d20924cbf8e25e7b11c7c502c ?
You get always get a thumbnail from the portal item if it exists. Once you have you portal item initialised you can call thumbnail and it will return an image if it exists.
ArcGIS Runtime SDK for iOS: AGSItem Class Reference
If you're asking how to create your own image/thumbnail for portal item.
You can load the webMap and once it's rendered you can call exportImage on mapView.
Can you please provide me some Example or URL?
If you are looking for an example for taking screenshot, we have a sample here. If not, can you elaborate on the use case you have or what you are trying to do?
Retrieving data ...