Sweney’s musical gift showed itself at an early age. While still a boy, he began to teach music in the public schools and lead Sunday school performances. At age 19, he started studying music in earnest under Professor Bauer, a celebrated German teacher. He took lessons on the violin and piano, and about this time was chosen leader of a choir. He was also in constant demand for children’s concerts and for conducting glee clubs.

At age 22, Sweney was called to teach in Dover, Delaware. When the American civil war broke out, he took charge of the band of the Third Delaware Regiment. After the war, Sweney became Professor of Music at the Pennsylvania Military Academy in West Chester, Pennsylvania. He worked there over 25 years, and received the degrees of Bachelor of Music (1876) and Doctor of Music (1886).

Sweney composed more than 1,000 hymn tunes, and collaborated with William Kirkpatrick on a number of hymn collections.