Air Carrier flight crew flying B777 aircraft reported jammed Nose Gear Tiller on taxi out.

Narrative

After pushing back from Gate XX facing SE at ZZZ and completing normal checklists and engine start; we were cleared to taxi to Runway XXR at XX via Taxiways XZ; XA; XB; XC; XD; XX. Initial taxi required a shallow turn to the right followed by a shallow turn to the left to establish the aircraft on Taxiway XZ. The first 90 degree turn was a right turn from XZ to XA. As I began to turn right the tiller responded normally through the first ~180 degrees of deflection; but then it suddenly became very difficult to move. As I added pressure it became impossible to move even with both hands on the tiller pulling with a lot of force. I began going wide on the turn and added right brake pedal pressure which helped bring the nose around. I could see that we would safely complete the turn; but the nose wheels came uncomfortably close to the edge of the taxiway for me. I would estimate well within 3-6 ft. of the painted taxiway edge. I don't recall my exact words; but I loudly said that I couldn't move the tiller or it had jammed. As I rolled out of the turn the tiller moved normally to the neutral; centered position. We were moving quite slowly now and I again mentioned that the tiller had jammed. It was then that the FO (First Officer) saw and removed his iPad cover from behind the retracted map table where he had stored it. He had placed it between the retracted map table and the cockpit trim in the vertical position; and the tiller had come into contact with it blocking free movement. After it had been removed tiller movement and aircraft steering returned to normal; the flight completed without further incident.