The difference between JS and Swift is that Swift compiles everything with static types. So JS just plods along and does one of it's funky things with types whe

The difference between JS and Swift is that Swift compiles everything with static types. So JS just plods along and does one of it's funky things with types when encountering the next instruction, but Swift actually needs hard types to be able to compile and run at all. So you need to provide them, or it figures them out by itself. There used to be this famous error about "too complex" statements. They still exist but got a lot less: "swift expression was too complex to be solved" http://stackoverflow.com/questions/29707622/bizarre-swift-compiler-error-expression-too-complex-on-a-string-concatenation http://stackoverflow.com/questions/29707622/bizarre-swift-co... Also check the second answer, it's actually the best.