CODEWITHSUNDEEP
iosautolayoutconstraintsmasonry
JokerV
JokerV

Reputation: 387

How to use Masonry mas_makeConstraints to avoid conflicts?

[self.line mas_makeConstraints:^(MASConstraintMaker *make) {
        make.centerY.equalTo(_line.superview).multipliedBy(0.5);
    }];

[self.line mas_updateConstraints:^(MASConstraintMaker *make) {
        make.centerY.equalTo(_line.superview).multipliedBy(1.66666);
    }];

    "<MASLayoutConstraint:0x14efa7170 UIView:0x14ef3f5a0.centerY == UIView:0x14ef3ec00.centerY * 0.5>",
    "<MASLayoutConstraint:0x15026dcb0 UIView:0x14ef3f5a0.centerY == UIView:0x14ef3ec00.centerY * 1.66666>"

When I try to update the constraints, there will be a conflict, how to use it correctly?

It looks like the update operation has created a new constraint instead of changing its value.

Can't it be applied in mas_updateConstraints?

Do I have to use mas_remakeConstraints?

Upvotes: 1

Views: 819

Answers (1)

夜一林风
夜一林风

Reputation: 1327

Apple doc says:

Unlike the other properties, the constant may be modified after constraint creation. Setting the constant on an existing constraint performs much better than removing the constraint and adding a new one that's just like the old but for having a new constant.

Let's paste some vanilla constraints below:

[NSLayoutConstraint constraintWithItem:view1
                                 attribute:NSLayoutAttributeTop
                                 relatedBy:NSLayoutRelationEqual
                                    toItem:superview
                                 attribute:NSLayoutAttributeTop
                                multiplier:1.0
                                  constant:padding.top]

According to the doc, mas_updateConstraints is supposed to change the constant value of an existing constraint, however, multiplier is not the constant part.

Use mas_remakeConstraints instead, according to the doc, which remove all the existing ones before installing new ones.

Upvotes: 1

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