關(guān)于約束
首先 Button.translatesAutoresizingMaskIntoConstraints = NO;
創(chuàng)建完按鈕再添加約束
NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:firstButton attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqualtoItem:self.view attribute:NSLayoutAttributeLeading multiplier:1.0f constant:20.f];
[self.view addConstraint:constraint];
總結(jié)一句話:始終遵循下面的規(guī)律:
- viewA.attribute = viewB.attributs*multiplier + constant