两个view约束控制底部隐藏

两个view控制底部隐藏 

1、底部隐藏
NSArray* constrains = self.ve_bottom.constraints;
    
    for (NSLayoutConstraint* constraint in constrains) {
        
        if (constraint.firstAttribute == NSLayoutAttributeHeight) {
            
            constraint.constant = 0.0;
            
        }
        
    }
    
2、更新上面view的距离底部的约束
    NSArray* constrains2 = self.ve_top.constraints;
    
    for (NSLayoutConstraint* constraint in constrains2) {
        
        if (constraint.secondItem == self.ve_top) {
            
            //据底部0
            if (constraint.firstAttribute ==NSLayoutAttributeBottom) {
                
                constraint.constant = 0.0;
                
                
            }
            
        }
        
    }