Incident happened during '1989' world tour date in Edmonton on Tuesday
Pop singer also reveals how Jay Z helped her to make friends with Kanye West
The costume was popularised by Perry's Super Bowl halftime show earlier this year
"I thought I was being called out," says pop singer after criticising Minaj in MTV VMA dispute
The singer relaxed tough rules placed on photographers at her performances following backlash
The singer accused of using all the power at Nationals Park in Washington DC
The pop singer says that it 'made her day'
The singer's label boss discussed the incident at a recent tech conference
MetLife Stadium performance also saw The Weeknd join Swift to perform live
Pop singer donated money to 11-year-old Naomi Oakes as she undergoes hospital treatment