WWDC Auto Layout

WWDC 2012 V202

Add the constraint to the two views closest ancestors, every view is considered an acestor of itself.
E.g:
– Two siblings, add constraint to parent view.
– Cousins, constraint to grand parent

viewDidLoad – good place where to set the constraints

po [[UIWindow keywindo] _autolayoutTrace] to visualize the AutoLayout

setTranslatesAutorezingingMaskIntoConstraints -> If not using Auto Layout, Springs and masks are translated into AutoLayout.

WWDC 2012 V228
For debugging:
knowing what constraint is affecting
[view constraintsAffectingLayoutForAxis: NSLayoutCosntraintOrientationHorizontal/Vertical]

[view exerciseAmbiguitiInLayout]

Animation can be applied to the view or to the Auto Layout property

CoreAnimation:
1) Adjust constraints
2) [UIView animateWithDuration: 0.5 animations:^{
[view layoutIfNeeded];
}];

NSLayoutContraint:
changing the constant of a NSLayoutConstraint permits efficient relayouts
on iOS this can only be animated with NSTimer and on tick changing constraint.constant value

Alignment Rect:
Used to calculate the bounds to algin,doesn’t need to be the frame

Intrisinsic Content Size
Equivalency with sizeToFit, sizeThatFits
It is a preferred size, is not settable, constraint set them with their priorities

Any time the content changes so that the intrinsic content size should change-> [self invalidateIntrinsicContext]
Use intrinsicContentSize as a better sizeToFit
NSRect alignmentRect = (NSRect) {NSZeroPoint, [control intrinsicContentSize]};
[control setFrameSize: [control frameForAlignmentRect:alignmentRect].size];

Localisation
RTL
AutoLayout uses leading and trainling and they flip automatically on

WWDC 2012 V232 Autolayout By Example

Arguments:
NSDoubleLocalizedStrings YES: Multiplies all the strings by two to debug the Layout
Simulate right to left
AppleTextDirection YES
NSForceRightToLeftWritingDirection YES

Draw view alignment rects
UIViewShowAlignmentRects YES

Localizing RTL
If an asset is not desired to flip on language change… In IB set direction instead to Leading to Trailing, to the specific direction