[swift-evolution] IUO type, treat nil as normal error, not fatal error

[Cao Jiannan]

Hi all,

I want to discuss the Implicitly Unwrapped Optional Type.

In Swift 1 and Swift2, when a variable declared as IUO type, its value should be non-nil. 
If its value is nil, it will crash the program when read the value.

I  believe it is better to let developer catch this event, treat it as normal error, and can be caught.

Thanks!

Jiannan