Autolayout helper

MB_Autolayout.m

- (void)ag_addSubview:(UIView *)subview withInsets:(UIEdgeInsets)insets {
    [self addSubview:subview];
    [subview setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self addConstraintFromSubview:subview forAttribute:NSLayoutAttributeTop withConstant:insets.top];
    [self addConstraintFromSubview:subview forAttribute:NSLayoutAttributeBottom withConstant:insets.bottom];
    [self addConstraintFromSubview:subview forAttribute:NSLayoutAttributeLeft withConstant:insets.left];
    [self addConstraintFromSubview:subview forAttribute:NSLayoutAttributeRight withConstant:insets.right];
}

- (BOOL)addConstraintFromSubview:(UIView *)subview forAttribute:(NSLayoutAttribute)attribute withConstant:(CGFloat)constantValue {
    if (constantValue == AGIneffectiveConstantValue) {
        return NO;
    }
    NSLayoutConstraint *constraint = [NSLayoutConstraint
                                      constraintWithItem:self
                                      attribute:attribute
                                      relatedBy:NSLayoutRelationEqual
                                      toItem:subview
                                      attribute:attribute
                                      multiplier:1.f
                                      constant:constantValue];
    [self addConstraint:constraint];
    return YES;
}