为masonry添加保护

 Pod::Spec.new do |s|
   s.name     = 'Masonry'
-  s.version  = '1.1.0'
+  s.version  = '1.1.0.yoho'
   s.license  = 'MIT'
   s.summary  = 'Harness the power of Auto Layout NSLayoutConstraints with a simplified, chainable and expressive syntax.'
   s.homepage = 'https://github.com/cloudkite/Masonry'

@@ -327,6 +327,12 @@ static char kInstalledConstraintsKey;
     if (!self.firstViewAttribute.isSizeAttribute && !self.secondViewAttribute) {
         secondLayoutItem = self.firstViewAttribute.view.superview;
         secondLayoutAttribute = firstLayoutAttribute;
+        
+        if (!secondLayoutItem) {
+            NSAssert(secondLayoutItem, @"YH_Mall : The secondItem is null or nil !!!!!");
+            return;
+        }
+
     }
     
     MASLayoutConstraint *layoutConstraint