print vs dump

Many of us start debugging with simple print(). Let’s say we have such a class:

class Abc {
    let a = "aa"
    let b = "bb"
}

and we have an instance of Abc as so:

let abc = Abc()

When we run the print() on the variable, the output is

App.Abc

while dump() outputs

App.Abc #0
- a: "aa"
- b: "bb"

As seen, dump() outputs the whole class hierarchy, while print() simply outputs the class name.

Therefore, dump() is especially useful for UI debugging

let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))

With dump(view) we get:

- <UIView: 0x108a0cde0; frame = (0 0; 100 100); layer = <CALayer: 0x159340cb0>> #0
   - super: UIResponder
     - NSObject

While print(view) we get:

<UIView: 0x108a0cde0; frame = (0 0; 100 100); layer = <CALayer: 0x159340cb0>>

There is more info on the class with dump(), and so it is more useful in debugging the class itself.