Oppo on Tuesday launched A78 smartphone in the mid-range segment in India. The 4G smartphone expands Oppo’s A series with features like 50MP main camera. The Oppo A78 has a 6.4 inch FHD+ AMOLED screen with 90Hz refresh rate and up to 600 nits of peak brightness. The Chinese smartphone maker has used a 5,000mAh battery in Oppo A78 that …