Apple's next generation iPhone, dubbed iPhone 5S or iPhone 6, will have a 'killer feature' to trump Samsung's new Galaxy S4 smartphone, an analyst has said.During an interview with CNBC on Monday, Morgan Stanley's Katy Huberty said that she expects the next-generation iPhone to spark a big comeback for Apple."I do believe that AAPL is approaching a bottom," she said, referring to Apple's struggling share price. "As you have heard, they are talking about returning more cash, and we think they will do that in the coming weeks. But people don't own AAPL for that. They own AAPL for innovation.""You saw Samsung Galaxy S4 come out last week, that shows you the innovation cards are up for grabs," Huberty continued. "What is lacking in that product [the S4] is a killer feature. We think that's where Apple will surprise this year.""This [iPhone] 5S cycle this year will be about a killer feature that drives consumers increasingly to the platform, and that increases the value of those 500 million [iOS] accounts," she added.