title: iOS auto-layout constraints broken in iOS 6, but fine in iOS7
body: <p>I'm currently setting up my UITableViewCell with iOS auto-layout using Masonry DSL. It's working fine in iOS 7, but in iOS 6 it's shouting a bunch of broken constraints warning like this:</p>
  
  <pre><code>Break on objc_exception_throw to catch this in the debugger.
  The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in &lt;UIKit/UIView.h&gt; may also be helpful.
  2014-03-13 14:41:07.422 clear[754:907] Unable to simultaneously satisfy constraints.
      Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
  (
      "&lt;MASLayoutConstraint:0x1ed1e180 UILabel:0x1ed18ec0.centerY == UIView:0x1ed6b2b0.centerY&gt;",
      "&lt;MASLayoutConstraint:0x1ed00f50 UILabel:0x1ed18ec0.centerY == UIView:0x1ed6b2b0.centerY&gt;"
  )
  
  Will attempt to recover by breaking constraint 
  &lt;MASLayoutConstraint:0x1ed1e180 UILabel:0x1ed18ec0.centerY == UIView:0x1ed6b2b0.centerY&gt;
  
  Break on objc_exception_throw to catch this in the debugger.
  The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in &lt;UIKit/UIView.h&gt; may also be helpful.
  2014-03-13 14:41:07.451 clear[754:907] Unable to simultaneously satisfy constraints.
      Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
  (
      "&lt;MASLayoutConstraint:0x1edf0010 UIView:0x1edef170.width == UIView:0x1edef170.height * 0.75&gt;",
      "&lt;MASLayoutConstraint:0x1ed309f0 UIView:0x1edef170.width == UIView:0x1edef170.height * 0.75&gt;"
  )
  
  Will attempt to recover by breaking constraint 
  &lt;MASLayoutConstraint:0x1edf0010 UIView:0x1edef170.width == UIView:0x1edef170.height * 0.75&gt;
  </code></pre>
  
  <p>One thing that I notice is that somehow some of the constraints (shown above) are duplicated, so iOS has to drop one of each. Code snippet attached below. Anyone can help me find out what the problem is and get rid of this warning message?</p>
  
  <p><strong>UITableViewCell updateConstraints</strong></p>
  
  <pre><code>- (void)updateConstraints
  {
      [super updateConstraints];
  
      [self.coverImage mas_makeConstraints:^(MASConstraintMaker *make) {
          make.left.equalTo(self.contentView).with.offset(20);
          make.top.equalTo(self.contentView).with.offset(5);
          make.bottom.equalTo(self.contentView).with.offset(-5);
  
          make.width.equalTo(self.coverImage.mas_height).multipliedBy(0.75);
      }];
  
      [self.containerView mas_makeConstraints:^(MASConstraintMaker *make) {
          make.left.equalTo(self.coverImage.mas_right).with.offset(10);
          make.centerY.equalTo(self.contentView).priorityLow();
      }];
  
      [self.titleLabel mas_makeConstraints:^(MASConstraintMaker *make) {
          make.left.equalTo(self.containerView);
          make.top.equalTo(self.containerView);
      }];
  
      [self.avatarImage mas_makeConstraints:^(MASConstraintMaker *make) {
          make.top.equalTo(self.titleLabel.mas_bottom).with.offset(5);
          make.left.equalTo(self.containerView);
          make.bottom.equalTo(self.containerView);
  
          make.width.equalTo(@20);
          make.height.equalTo(@20);
      }];
  
      [self.authorLabel mas_makeConstraints:^(MASConstraintMaker *make) {
          make.left.equalTo(self.avatarImage.mas_right).with.offset(5);
          make.centerY.equalTo(self.avatarImage);
      }];
  
      [self.dateLabel mas_makeConstraints:^(MASConstraintMaker *make) {
          make.right.equalTo(self.contentView).with.offset(-10);
          make.top.equalTo(self.contentView).with.offset(5);
      }];
  }
  </code></pre>