Autolayout - arrange elements vertically with space in between programatically? - ios

Question

I'm currently manually positioning my UI elements, which gets annoying if I update the text or add elements as I have to recalculate all the positions each time.
Is there a way using autolayout to size and positions the elements, for example as follows, no matter how much text the labels contain?
UILabel (multiline, variable height)
[20px gap]
UILabel (multiline, variable height)
[20px gap]
UIButton

Answer 1

Yes, it will look something like this
#implementation MyClass {
NSDictionary *_viewsDictionary;
}
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
if (self) {
// First create your controls - you can just use CGRectZero
_label1 = [[UILabel alloc] initWithFrame:CGRectZero];
_label1 setText:#"Some text";
_label2 = [[UILabel alloc] initWithFrame:CGRectZero];
_label2 setText:#"Some text 2";
_button = [[UIButton alloc] initWithFrame:CGRectZero];
// Then just add them to your as a sub view
[self addSubview:self.currentBalanceLabel];
[self addSubview:_nameLabel];
[self addSubview:_button];
// Put them in an NSDictionary - this is a macro and will be used when setting up the contraints below
_viewsDictionary = NSDictionaryOfVariableBindings(_nameLabel, _currentBalanceLabel,_button);
// This tells the view to run update contraints
[self setNeedsUpdateConstraints];
[self updateConstraintsIfNeeded];
}
}
- (void)updateConstraints
{
[super updateConstraints];
// Using the _viewsDictionary, we must tell always tell how all the controls will be setup both
// horizontally and vertically. In this case wear are going to tell the label to take the entire width
// The rest of the vies will be aligned on the left below
NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:#"H:|-[_label1]-|"
options:0
metrics:nil
views:_viewsDictionary];
//Add the contraints
[self addConstraints:constraints];
// Next setup the vertical contraints. This is what you asked about spefically, label - 20 - label - 20 - button
constraints = [NSLayoutConstraint constraintsWithVisualFormat:#"V:|-[_labelq]-20-[_label2]-20-[_button]"
options: NSLayoutFormatAlignAllLeft
metrics:nil
views:_viewsDictionary];
[self addConstraints:constraints];
}
#end