[wolfsir]

Int is a 64-bit data type and Int32 is 32-bits. The compiler refuses to infer that you want to lose data. Converting the other way, the compiler refuses to infer that you want to bloat your data.

CGFloat, depending on the runtime, may either be a Float or a Double, so explicitly converting to and from it is required.

Rather than create a byzantine set of rules about whether it is "safe" to convert from one type to another, Swift wisely requires that all type conversions be explicit.