iOS Auto layout Rows - ios

Question

I'm trying to understand auto layout better and I created some static methods that can help me out. Now I'm trying to setup an array of views in like a tableview structure (in rows). This works kinda.
See here my problem:
To achieve this I use this code:
//In the update constraints method
UIView *view1 = [self createView];
view1.backgroundColor = [UIColor redColor];
UIView *view2 = [self createView];
view2.backgroundColor = [UIColor yellowColor];
[self addSubview:view1];
[self addSubview:view2];
[self addConstraints:[DXVFL row:#[view1, view2] inView:self]];
//The row method
+ (NSArray *) row:(NSArray const *)views inView:(UIView const *)superview {
NSMutableArray *constraints = [NSMutableArray new];
CGFloat multiplier = 1.f / [views count];
UIView *prev = nil;
for (UIView *view in views) {
if (!view.hidden) {
[constraints addObject:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:superview attribute:NSLayoutAttributeWidth multiplier:1.f constant:0.f]];
[constraints addObject:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:superview attribute:NSLayoutAttributeHeight multiplier:multiplier constant:0.f]];
if (prev) {
[constraints addObject:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:prev attribute:NSLayoutAttributeBottom multiplier:1.f constant:0.f]];
}
prev = view;
}
}
return [constraints copy];
}
So this part works (I guess). But when I want to split the yellow view again in rows. The views are always added into the top region?
In the update constraints method I do this:
UIView *view1 = [self createView];
view1.backgroundColor = [UIColor redColor];
UIView *view2 = [self createView];
view2.backgroundColor = [UIColor yellowColor];
[self addSubview:view1];
[self addSubview:view2];
UIView *view3 = [self createView];
UIView *view4 = [self createView];
[view2 addSubview:view3];
[view2 addSubview:view4];
[self addConstraints:[DXVFL row:#[view1, view2] inView:self]];
[view2 addConstraints:[DXVFL row:#[view3, view4] inView:view2]];
But I want those two rows in the bottom? What am I doing wrong?

Answer 1

Off the top of my head:
You need to add a constraint to tell it to align the view to the top of the superview. At the moment, you just set the height and width but you don't tell it where to put its top edge.
Try changing your code to this:
if (!prev) {
[constraints addObject:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:superview attribute:NSLayoutAttributeTop multiplier:1.f constant:0.f]];
} else {
[constraints addObject:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:prev attribute:NSLayoutAttributeBottom multiplier:1.f constant:0.f]];
}