K-pop supergroup BTS has secured its seventh No. 1 hit on the US Billboard's main singles chart, debuting atop the chart with its latest single, "Swim." The upbeat alternative pop track, which leads the band's fifth studio album, "Arirang," topped the Billboard Hot 100 for the week of April 4. It outpaced Ella Langley's "Choosin' Texas" to claim the highest ranking, according to a Billboard preview released Monday (US time). The milestone adds "Swim" to the act's impressive roster of Billboard t