OAStackView/Pod/Classes/OAStackView+Constraint.m at f9c6509660de59c5fa5d7d7799c4bcefe7301ac3 · nsomar/OAStackView · GitHub

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//
//  OAStackView+Constraint.m
//  Pods
//
//  Created by Omar Abdelhafith on 14/06/2015.
//
//

#import "OAStackView+Constraint.h"

@implementation OAStackView (Constraint)

- (NSArray*)constraintsBetweenView:(UIView*)firstView andView:(UIView*)otherView
                            inAxis:(UILayoutConstraintAxis)axis includeReversed:(BOOL)includeReversed {
  NSMutableArray *arr = [@[] mutableCopy];

  for (NSLayoutConstraint *constraint in self.constraints) {
    BOOL viewMatches = (firstView == constraint.firstItem && otherView == constraint.secondItem);

    if (includeReversed) {
      viewMatches = viewMatches || (firstView == constraint.secondItem && otherView == constraint.firstItem);
    }

    BOOL isCorrectAxis = [self isConstraint:constraint affectingAxis:axis];

    if (viewMatches && isCorrectAxis) {
      [arr addObject:constraint];
    }
  }

  return arr;
}

- (NSArray*)firstConstraintAffectingView:(UIView*)superView andView:(UIView*)childView inAxis:(UILayoutConstraintAxis)axis {
  return [self constraintAffectingView:superView andView:childView inAxis:axis isLast:NO];
}

- (NSArray*)lastConstraintAffectingView:(UIView*)superView andView:(UIView*)childView inAxis:(UILayoutConstraintAxis)axis {
  return [self constraintAffectingView:superView andView:childView inAxis:axis isLast:YES];
}

- (NSArray*)constraintAffectingView:(UIView*)superView andView:(UIView*)childView inAxis:(UILayoutConstraintAxis)axis isLast:(BOOL)isLast {
  if (childView == nil || superView == nil) {
    return nil;
  }

  NSMutableArray *arr = [@[] mutableCopy];

  for (NSLayoutConstraint *constraint in self.constraints) {
    BOOL isBetweenViews = [self isConstraint:constraint betweenView:superView andView:childView];
    if (!isBetweenViews) { continue; }

    BOOL isOnAxis = [self isConstraint:constraint affectingAxis:axis];
    if (!isOnAxis) { continue; }

    BOOL matches = NO;

    if (axis == UILayoutConstraintAxisHorizontal) {

      if (isLast) {
        matches =
        (constraint.firstAttribute == NSLayoutAttributeRight || constraint.firstAttribute == NSLayoutAttributeTrailing) &&
        (constraint.secondAttribute == NSLayoutAttributeRight || constraint.secondAttribute == NSLayoutAttributeTrailing);
      } else {
        matches =
        (constraint.firstAttribute == NSLayoutAttributeLeft || constraint.firstAttribute == NSLayoutAttributeLeading) &&
        (constraint.secondAttribute == NSLayoutAttributeLeft || constraint.secondAttribute == NSLayoutAttributeLeading);
      }

    } else {

      if (isLast) {
        matches =
        (constraint.firstAttribute == NSLayoutAttributeBottom) &&
        (constraint.secondAttribute == NSLayoutAttributeBottom);
      } else {
        matches =
        (constraint.firstAttribute == NSLayoutAttributeTop) &&
        (constraint.secondAttribute == NSLayoutAttributeTop);
      }

    }

    if (matches) {
      [arr addObject:constraint];
    }
  }

  return arr;
}

- (BOOL)isConstraint:(NSLayoutConstraint*)constraint betweenView:(UIView*)firstView andView:(UIView*)secondView {
  return (firstView == constraint.firstItem && secondView == constraint.secondItem) ||
  (firstView == constraint.secondItem && secondView == constraint.firstItem);
}

- (NSArray*)constraintsBetweenView:(UIView*)firstView andView:(UIView*)otherView inAxis:(UILayoutConstraintAxis)axis {
  return [self constraintsBetweenView:firstView andView:otherView inAxis:axis includeReversed:YES];
}

- (NSArray*)constraintsAffectingView:(UIView*)view {
  NSMutableArray *arr = [@[] mutableCopy];
  [arr addObjectsFromArray:[self constraintsAffectingView:view inAxis:UILayoutConstraintAxisVertical]];
  [arr addObjectsFromArray:[self constraintsAffectingView:view inAxis:UILayoutConstraintAxisHorizontal]];
  return arr;
}

- (NSArray*)constraintsAffectingView:(UIView*)view inAxis:(UILayoutConstraintAxis)axis {
  NSMutableArray *arr = [@[] mutableCopy];

  for (NSLayoutConstraint *constraint in self.constraints) {
    BOOL viewMatches = (view == constraint.firstItem || view == constraint.secondItem);
    BOOL constraintAffectingAxis = [self isConstraint:constraint affectingAxis:axis];

    if (viewMatches && constraintAffectingAxis) {
      [arr addObject:constraint];
    }
  }

  return arr;
}

- (void)removeDecendentConstraints {
  for (NSInteger i = self.constraints.count - 1; i >= 0 ; i--) {
    NSLayoutConstraint *constraint = self.constraints[i];
    if ([self.subviews containsObject:constraint.firstItem] ||
        [self.subviews containsObject:constraint.secondItem]) {
      [self removeConstraint:constraint];
    }
  }
}

- (BOOL)isConstraint:(NSLayoutConstraint*)constraint affectingAxis:(UILayoutConstraintAxis)axis {
  return [self isConstraintAttribute:constraint.firstAttribute affectingAxis:axis] ||
  [self isConstraintAttribute:constraint.secondAttribute affectingAxis:axis];
}

- (BOOL)isConstraintAttribute:(NSLayoutAttribute)attribute affectingAxis:(UILayoutConstraintAxis)axis {
  switch (axis) {
    case UILayoutConstraintAxisHorizontal:
      return attribute == NSLayoutAttributeLeft || attribute == NSLayoutAttributeRight ||
      attribute == NSLayoutAttributeLeading || attribute == NSLayoutAttributeTrailing ||
      attribute == NSLayoutAttributeCenterX || attribute == NSLayoutAttributeWidth
#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_7_1
      || attribute == NSLayoutAttributeLeftMargin || attribute == NSLayoutAttributeRightMargin ||
      attribute == NSLayoutAttributeLeadingMargin || attribute == NSLayoutAttributeTrailingMargin ||
      attribute == NSLayoutAttributeCenterXWithinMargins
#endif
      ;
      break;

    case UILayoutConstraintAxisVertical:
      return attribute == NSLayoutAttributeTop || attribute == NSLayoutAttributeBottom ||
      attribute == NSLayoutAttributeCenterY || attribute == NSLayoutAttributeHeight ||
      attribute == NSLayoutAttributeBaseline
#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_7_1
      || attribute == NSLayoutAttributeLastBaseline || attribute == NSLayoutAttributeFirstBaseline ||
      attribute == NSLayoutAttributeTopMargin || attribute == NSLayoutAttributeBottomMargin ||
      attribute == NSLayoutAttributeCenterYWithinMargins
#endif
      ;
      break;

    default:
      return NO;
      break;
  }
}

@end