Learn Swift Programming with No-Charge Books

Besides the official Swift Programming Language book (featured below), there are no other good quality open source Swift books. Given the short passage of time since Apple open sourced the language, this isn’t that surprising. There was an interesting ???The Swift Book???, which is available under the MIT license, but it is mostly incomplete and updates have stalled. Fortunately, there are some excellent Swift books which can be read without charge which fill the void.