[iMore Question]

When I connect my iphone with the charge I need to press it a little bit, and if I use the mobile while charging it lost the connection.

[dpscott]

Likely to have a faulty cable. Try replacing the cable.
As always I'd recommend official ones but other ones do work

[Spencerdl]

Good Job DpScott

[Wotchered]

almost certainly your connector,make sure socket is clear of fuzz

[Rob Phillips]

Yeah it's the cable. As @dpscott already mentioned make sure it's either an official Apple cable or that it's MFi (Made for iPhone) certified.