Mark Papermaster, the Apple executive in charge of hardware for the company’s flagship iPhone, has left the company in the wake of widely reported problems with the antenna of the recently introduced iPhone 4. It is not clear if Mr. Papermaster was ousted or left on his own accord. Reached on his cellphone, Mr. Papermaster declined to comment. In a statement, an Apple spokesman, Steve Dowling, confirmed Mr. Papermaster’s departure. Mr. Dowling said Mr. Papermaster “is leaving the company and Bob Mansfield, senior vice president of Macintosh hardware engineering, is assuming his responsibilities.” ... Mr. Papermaster, who was listed as...