A piece of code for doing auto layout in a UIView subclass

UIViewSubclass.m

// Declare this property in your header / private header
@property (nonatomic, strong) NSMutableArray *updatingConstraints;

- (void)updateConstraints {
    if (self.updatingConstraints) {
        [self removeConstraints:self.updatingConstraints];
    }
    self.updatingConstraints = [NSMutableArray array];
    
    // Create and add all of your constraints here
    
    [super updateConstraints];
}

- (void)addConstraint:(NSLayoutConstraint *)constraint {
    [super addConstraint:constraint];
    [self.updatingConstraints addObject:constraint];
}

- (void)addConstraints:(NSArray *)constraints {
    [super addConstraints:constraints];
    [self.updatingConstraints addObjectsFromArray:constraints];
}