The ruler who developed the Iqtadari system in India was Iltutmish.

The Iqtadari system was a unique administrative and revenue system developed in medieval India. It was introduced by Iltutmish, the third ruler of the Delhi Sultanate, who reigned from 1211 to 1236. The system played a crucial role in the governance and revenue collection of the Delhi Sultanate.

Explanation:

Introduction of the Iqtadari System:
- Iltutmish introduced the Iqtadari system to effectively manage the vast territories under his control.
- Under this system, the empire was divided into several Iqtas, which were large administrative units.
- Each Iqta was assigned to an Iqtadar, who acted as its administrator and revenue collector.
- The Iqtadar would receive a share of the revenue collected from the Iqta as his salary and was responsible for maintaining law and order.

Administration and Revenue Collection:
- The Iqtadari system helped in the efficient administration of the empire by decentralizing power and delegating authority to local administrators.
- The Iqtadars had significant administrative powers within their respective Iqtas, including the authority to appoint officials, maintain an army, and dispense justice.
- They were responsible for collecting revenue from the land, which was divided into several categories based on fertility and productivity.
- The revenue collected from the land was divided into the Khalisa (royal treasury) and the Iqtadar's share.
- The Iqtadar's share was usually fixed at 50% of the revenue collected, although it could vary depending on the circumstances.

Advantages and Significance of the Iqtadari System:
- The Iqtadari system helped in consolidating the authority of the Delhi Sultanate by ensuring effective governance and revenue collection.
- It provided a stable source of income for the administration and helped in financing the empire's military campaigns and infrastructure development.
- The system also facilitated the integration of the local population into the administration, as the Iqtadars often relied on local officials and intermediaries for revenue collection.
- Moreover, the Iqtadars played a crucial role in maintaining law and order within their Iqtas, thus ensuring stability and security.

Conclusion:
In conclusion, Iltutmish introduced the Iqtadari system in India as an effective administrative and revenue collection system. This system played a pivotal role in the governance of the Delhi Sultanate and helped in consolidating its authority over the vast territories under its control.