Update README.md

README.md

@@ -204,9 +204,12 @@ make.center.equalTo(superview).centerOffset(CGPointMake(-5, 10))
 
 ## Hold on for dear life
 
-Sometimes you need to reference constraints so you can modify them at a later stage. This lets you animate or remove/replace constraints.
+Sometimes you need modify existing constraints inorder to animate or remove/replace constraints.
+In Masonry there are two common approaches for updating constraints.
+
+#### 1. References
 You can hold on to a reference of a particular constraint by assigning the result of a constraint make expression to a local variable or a class property.
-You could also reference multiple constraints by storing them away in an array. You can see a demo of this in the animation example in **Masonry iOS Examples** project.
+You could also reference multiple constraints by storing them away in an array.
 
 ```obj-c
 // in public/private interface
@@ -225,6 +228,28 @@ You could also reference multiple constraints by storing them away in an array.
 [self.topConstraint uninstall];
 ```
 
+#### 2. mas_updateConstraints
+Alternatively if you are only updating the constant value of the constraint you can use the convience method `mas_updateConstraints` instead of `mas_makeConstraints`
+
+```
+// this is Apple's recommended place for adding/updating constraints
+// this method can get called multiple times in response to setNeedsUpdateConstraints
+// which can be called by UIKit internally or in your code if you need to trigger an update to your constraints
+- (void)updateConstraints {
+    [super updateConstraints];
+
+    [self.growingButton mas_updateConstraints:^(MASConstraintMaker *make) {
+        make.center.equalTo(self);
+        make.width.equalTo(@(self.buttonSize.width)).priorityLow();
+        make.height.equalTo(@(self.buttonSize.height)).priorityLow();
+        make.width.lessThanOrEqualTo(self);
+        make.height.lessThanOrEqualTo(self);
+    }];
+}
+```
+
+You can find more detailed examples of both approaches in the **Masonry iOS Examples** project.
+
 ## When the ^&*!@ hits the fan!
 
 Laying out your views doesn't always goto plan. So when things literally go pear shaped, you don't want to be looking at console output like this: