Proportional resizing of buttons in UIStackView

Question

I need to layout 5 buttons as in this image:

I need them to resize proportionally on different devices.

I have this code in a method which sets up a view with 5 buttons.

UIStackView *stackView = [[UIStackView alloc]init];

// Add buttons to stackView (buttons are initialised)
[stackView addArrangedSubview:_button1];
[stackView addArrangedSubview:_button2];
[stackView addArrangedSubview:_button3];
[stackView addArrangedSubview:_button4];
[stackView addArrangedSubview:_button5];

stackView.translatesAutoresizingMaskIntoConstraints = false;
[self.view addSubview:stackView];

stackView.axis = UILayoutConstraintAxisVertical;
stackView.distribution = UIStackViewDistributionFillEqually;
stackView.spacing = 5;

//Layout Constraints for stackView
[stackView.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = true;
[stackView.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = true;

// 80% of screen height should be used for buttons
CGFloat screenHeightAvailableForButtons = 80/100;
// Calculate multiplier for height of the buttons (5 buttons)
CGFloat buttonMultiplier = screenHeightAvailableForButtons /5;
// 25% of screen width should be used for buttons
CGFloat screenWidthMultiplier =  25/100;

[_button1.widthAnchor constraintEqualToAnchor:self.view.widthAnchor multiplier: screenWidthMultiplier].active = true;
[_button1.heightAnchor constraintEqualToAnchor: self.view.heightAnchor multiplier: buttonMultiplier].active = true;

[_button2.widthAnchor constraintEqualToAnchor:self.view.widthAnchor multiplier: screenWidthMultiplier ].active = true;
[_button2.heightAnchor constraintEqualToAnchor: self.view.heightAnchor multiplier: buttonMultiplier].active = true;

[_button3.widthAnchor constraintEqualToAnchor:self.view.widthAnchor multiplier: screenWidthMultiplier ].active = true;
[_button3.heightAnchor constraintEqualToAnchor: self.view.heightAnchor multiplier: buttonMultiplier].active = true;

[_button4.widthAnchor constraintEqualToAnchor:self.view.widthAnchor multiplier: screenWidthMultiplier ].active = true;
[_button4.heightAnchor constraintEqualToAnchor: self.view.heightAnchor multiplier: buttonMultiplier].active = true;

[_button5.widthAnchor constraintEqualToAnchor:self.view.widthAnchor multiplier: screenWidthMultiplier ].active = true;
[_button5.heightAnchor constraintEqualToAnchor: self.view.heightAnchor multiplier: buttonMultiplier].active = true;

This code returns a blank view. Am I using the methods incorrectly?
I can't work out what I am doing wrong. I need this done programmatically in objective c.

thanks

Answer 1

For your case, you don't need to set the constraints inside the stack view for buttons. Stack view will handle this automatically.

Try this

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    UIStackView *stackView = [[UIStackView alloc]initWithFrame:self.view.bounds];
    stackView.backgroundColor = [UIColor darkGrayColor];
    _button1 = [UIButton buttonWithType:UIButtonTypeSystem];
    [_button1 setTitle:@"Button 1" forState:UIControlStateNormal];
    _button1.translatesAutoresizingMaskIntoConstraints = NO;
    _button1.backgroundColor = [UIColor lightGrayColor];

    _button2 = [UIButton buttonWithType:UIButtonTypeSystem];
    [_button2 setTitle:@"Button 2" forState:UIControlStateNormal];
    _button2.translatesAutoresizingMaskIntoConstraints = NO;
    _button2.backgroundColor = [UIColor lightGrayColor];

    _button3 = [UIButton buttonWithType:UIButtonTypeSystem];
    [_button3 setTitle:@"Button 3" forState:UIControlStateNormal];
    _button3.translatesAutoresizingMaskIntoConstraints = NO;
    _button3.backgroundColor = [UIColor lightGrayColor];


    _button4 = [UIButton buttonWithType:UIButtonTypeSystem];
    [_button4 setTitle:@"Button 4" forState:UIControlStateNormal];
    _button4.translatesAutoresizingMaskIntoConstraints = NO;
    _button4.backgroundColor = [UIColor lightGrayColor];

    _button5 = [UIButton buttonWithType:UIButtonTypeSystem];
    [_button5 setTitle:@"Button 5" forState:UIControlStateNormal];
    _button5.translatesAutoresizingMaskIntoConstraints = NO;
    _button5.backgroundColor = [UIColor lightGrayColor];

    // Add buttons to stackView (buttons are initialised)
    [stackView addArrangedSubview:_button1];
    [stackView addArrangedSubview:_button2];
    [stackView addArrangedSubview:_button3];
    [stackView addArrangedSubview:_button4];
    [stackView addArrangedSubview:_button5];

    stackView.translatesAutoresizingMaskIntoConstraints = false;
    [self.view addSubview:stackView];

    stackView.axis = UILayoutConstraintAxisVertical;
    stackView.distribution = UIStackViewDistributionFillEqually;
    stackView.alignment = UIStackViewAlignmentFill;
    stackView.spacing = 5;

    //Layout Constraints for stackView
    [stackView.layoutMarginsGuide.topAnchor constraintEqualToAnchor:self.view.layoutMarginsGuide.topAnchor].active = true;
    [stackView.layoutMarginsGuide.bottomAnchor constraintEqualToAnchor:self.view.layoutMarginsGuide.bottomAnchor].active = true;
    // 25% of screen width should be used for buttons
    [stackView.widthAnchor constraintEqualToAnchor:self.view.widthAnchor multiplier:25.0/100.0].active = true;
    [stackView.layoutMarginsGuide.centerXAnchor constraintEqualToAnchor:self.view.layoutMarginsGuide.centerXAnchor].active = true;

}