0x00 Lesson
I already said that variables
have that name because their values can change
over time, and
that is often useful. However, very often you want to set a value once
and never
change it, and so we have an alternative to the var keyword called let.
The let keyword creates constants
, which are values that can be set once and never again
.
For example:
let taylor = "swift"
If you try to change that, Xcode will refuse to run your code. It’s a form of safety: when you use constants you can no longer change something by accident.
When you write your own Swift code, you should always use let unless you specifically want to change a value. In fact, Xcode will warn you if you use var then don 't change the variable.
0x01 Tips
use let first, then consider var
0x02 我的小作品
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