London: Singer Taylor Swift says she "can't imagine" her life without Selena Gomez. The 26-year-old singer and songwriter gushed about Gomez on social media in a heartfelt birthday message to the star, who turned 24 on Friday. Swift posted an old photograph of the two of them posing together while forming the shape of a heart with their hands, reports femalefirst.co.uk. The “Bad Blood” hitmaker captioned the image, which was shared on her Instagram account, with the caption: "Going through old pictures today, because Selena Gomez just turned 24! I can't imagine my life without you, Selena. HAPPY BIRTHDAY." For her birthday, Gomez asked fans to celebrate her special day by donating to a charity, which will help to prevent a cure for Lupus disease.