AwakeFromNib auto layout stretch UIlabel to spacing on both side programmatically - ios

Question

I am trying to add a UIlabel to a UIView class.
it should be in the following format -15-Label(stretch to max width)-15.
Top spacing=15 and height fixed to 30.
Two issues with the following code:-
1) Label does not stretch to max width
2) Right side spacing does not show up , if the text it too long.
-(void)awakeFromNib{
[super awakeFromNib];
view1 =[[UILabel alloc] init];
view1.translatesAutoresizingMaskIntoConstraints=NO;
[self addSubview:view1];
view1.text= #"Hello";
NSDictionary *constraintViews=
#{#"view1":view1};
NSDictionary *metrics=#{#"spacing":#(15)};
NSArray *hConstraints=[NSLayoutConstraint constraintsWithVisualFormat:#"H:|-spacing-[view1]-spacing-|" options:NSLayoutFormatAlignAllCenterX metrics:metrics views:allViews];
NSArray *vConstraints=[NSLayoutConstraint constraintsWithVisualFormat:#"V:|-spacing-[view1(30)]" options:0 metrics:metrics views:constraintViews];
[self addConstraints:hConstraints];
[self addConstraints:vConstraints];
}

Answer 1

1)
Update the horizontal constraints like so:
[NSLayoutConstraint constraintsWithVisualFormat:#"H:|-spacing-[view1]-spacing#751-|" options:NSLayoutFormatAlignAllCenterX metrics:metrics views:constraintViews];
Try adding the line below:
[view1 setContentHuggingPriority:UILayoutPriorityHigh forAxis:UILayoutConstraintAxisHorizontal];
2) I always set the numberOfLines property of a label to 0 by default, so that the label will autoresize vertically if the text needs to be shown in two or more lines. That being said, you would need to remove the fixed height constraint and the label will be the size of the it's contents like so:
view1.numberOfLines = 0;
NSArray *vConstraints=[NSLayoutConstraint constraintsWithVisualFormat:#"V:|-spacing-[view1]" options:0 metrics:metrics views:constraintViews];
I hope this helps.

Answer 2

I used this generic method for applying constraints of childView wrt to ParentView.Just pass your views to this method.
+ (void)applyConstraints:(UIView *)pChildView withSuperView:(UIView *)pParentView {
pChildView.translatesAutoresizingMaskIntoConstraints = NO;
// Width.
CGFloat widthValue = pParentView.frame.size.width;
[pParentView addConstraint:[NSLayoutConstraint constraintWithItem:pChildView attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual toItem:pParentView
attribute:NSLayoutAttributeWidth multiplier:1.0 constant:widthValue]];
// Height.
CGFloat heightValue = pParentView.frame.size.height;
[pParentView addConstraint:[NSLayoutConstraint constraintWithItem:pChildView attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual toItem:pParentView
attribute:NSLayoutAttributeHeight multiplier:1.0 constant:heightValue]];
// X margin.
[pParentView addConstraint:[NSLayoutConstraint constraintWithItem:pChildView attribute:NSLayoutAttributeCenterXWithinMargins
relatedBy:NSLayoutRelationEqual toItem:pParentView
attribute:NSLayoutAttributeCenterXWithinMargins multiplier:1.0 constant:0]];
// Y margin.
[pParentView addConstraint:[NSLayoutConstraint constraintWithItem:pChildView attribute:NSLayoutAttributeCenterYWithinMargins
relatedBy:NSLayoutRelationEqual toItem:pParentView
attribute:NSLayoutAttributeCenterYWithinMargins multiplier:1.0 constant:0]];
}