Swift Considerations (16)--optional chain

Optional Chain (Optional Chaining)We all know what "can be chosen" is. So what are the optional chains, for example, to explain:
struct myname{var name}
struct MyInfo {var myname:myname? = MyName ()}
Class MyClass {var structinstance:myinfo?

= MyInfo ()}
Here are two structs and one class, when. When this class is instantiated: var myinstance = MyClass () All of the optional properties are initialized because I write the default values.

if let name = myinstance.info?.myname?.name {(thanks to Swift Technical Exchange first platform (355277) group Friends week old Wet (974871365) indicates member name error)
If let name = myinstance.structinstance?. MyName?

. name {println (name)} else {println ("some info is nil")}
In the Scarlet Letter section, you can see that it is a series of optional values that are used.

This is called an optional chain. Here I also used a very early note mentioned in the IF let name = selectable {...} this syntax.
This is due to: in the optional chain, no matter what part of the optional parse failure (value nil), then the entire optional chain result is nil.
Of course, we may actually want to use the first link! "To allow an optional chain to return an exact value, rather than an optional value, for example: let name = Myinstance.info!. MyName!. Name but, in most cases, we don't know who's going to change the code. Who will change the implementation of a package. Assuming the wrong resolution of an optional value (a value of nil can be selected), then the consequences of only one, our program will be blown off ...

。 So, don't do this!

！。！

！
This chapter says something like this.

。。

As for what call function, use subscript, do not need to say again, logical ability normal human. will be used directly.

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Swift Considerations (16)--optional chain