lazy var or let for UIButton - ios

Question

When i want to add a UIButton in a view controller's view, here are the ways:
First
let button: UIButton = UIButton()
then configure properties in viewDidLoad method.
Second
lazy var button: UIButton = {
let buttonTemp = UIButton()
buttonTemp.backgroundColor = UIColor.clearColor()
button.addTarget(self, action: "connect", forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(buttonTemp)
return buttonTemp
}()
Third
let button: UIButton = {
let button = UIButton(type: .Custom)
button.backgroundColor = UIColor.greenColor()
return button
}()
My question is which way should i use or which way is better?
I dislike the first way because i have to add an extra method to configure other properties.
Second is ok for me, i just need call button anywhere i want to.
I think use let is suit the best so i use the third way, but the thing is i can't call self, which is if i add this link in the closure:
button.addTarget(self, action: "connect", forControlEvents: UIControlEvents.TouchUpInside)
I got the error:
ViewController.swift:24:26: Cannot convert value of type 'NSObject -> () -> ViewController' to expected argument type 'AnyObject?'
So i have add this line(any line with self) out of this closure. Any way can solve this?
Summary, which way is better or suit? Or any better way? thanks!
EDIT:
When i am using Objective C, i'd like use getter in this way
- (UIButton *) button {
if (!_button) {
_button = [[UIButton alloc] init];
_button.backgroundColor = [UIColor redColor];
...
}
return _button;
}
so my viewDidLoad will be clean and looks good:
- (void) viewDidLoad {
...
[self.view addSubview:self.button];
...
}

Answer 1

Styles obviously vary, but where I work we've standardized on the following approach:
class ViewController: UIViewController {
private var button: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
button = {
let button = UIButton(type: .Custom)
button.addTarget(self, action: "buttonTouched:", forControlEvents: .TouchUpInside)
button.otherProperty = ...
return button
}()
view.addSubview(button)
// add constraints for button
}
func buttonTouched(sender: UIButton) {
print("boop")
}
}
The problem with all of your approaches is that:
They're very verbose and not contained in a function, and
You don't have access to self as you've seen
With the approach above (using a force-unwrapped optional), you get the benefit of deferred initialization (i.e. everything happens in viewDidLoad()), you know because you own the object that button will never be nil (thus you don't have to use conditional binding all over the place), and you get contained initialization for all of your UIView properties in one place.
You can obviously (and we do) make your viewDidLoad() function look like this:
override func viewDidLoad() {
super.viewDidLoad()
createViews()
addSubviews()
addViewConstraints()
}
Then you get even better specialization in your functions and your code stays organized.