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    <p>The <code>topLayoutGuide</code> and <code>bottomLayoutGuide</code> properties are inherited from <a href="https://developer.apple.com/library/ios/documentation/uikit/reference/UIViewController_Class/Reference/Reference.html#//apple_ref/occ/instp/UIViewController/topLayoutGuide">UIViewController</a> and implements the <a href="https://developer.apple.com/library/ios/documentation/uikit/reference/UILayoutSupport_Protocol/Reference/Reference.html#//apple_ref/occ/intf/UILayoutSupport">UILayoutSupport</a> protocol. They are designed to be used with <code>AutoLayout</code>, but can also be used directly without the use of <code>AutoLayout</code>. </p> <p>In the case of <code>topLayoutGuide</code>, the property indicates the highest vertical extent for content that you don't want to appear behind a translucent or transparent UIKit bar (such as a status or navigation bar). So, if your view controller has been pushed onto a <code>UINavigationController</code> stack, <code>topLayoutGuide</code> will tell you how many points from the top of the screen the status bar and navigation bar cover. You can use this value scroll content in a <code>UIScrollView</code> to just below the navigation bar or ensure other content in your view isn't being covered by the <code>UINavigationBar</code>.</p> <p>Keep in mind that the value of <code>topLayoutGuide</code> depends on the view controller and whether or not it's contained within another view controller. From Apple's <code>UIViewController</code> documentation: </p> <blockquote> <p>The object that constrains the value for this property depends on whether or not the view controller is a child of a container view controller (such as a navigation or tab bar controller), as follows:</p> <p>• A view controller not within a container view controller constrains this property to indicate the bottom of the status bar, if visible, or else to indicate the top edge of the view controller's view. </p> <p>• A view controller within a container view controller does not set this property's value. Instead, the container view controller constrains the value to indicate: </p> <ul> <li><p>The bottom of the navigation bar, if a navigation bar is visible </p></li> <li><p>The bottom of the status bar, if only a status bar is visible </p></li> <li><p>The top edge of the view controller’s view, if neither a status bar nor navigation bar is visible</p></li> </ul> </blockquote> <p>Here's a piece of code I use to move a <code>UITextField</code> in response to the showing of the keyboard. I move the textfield to just below the navigation bar.</p> <pre><code>CGFloat length = self.topLayoutGuide.length; _feedback.frame = CGRectMake(_feedback.frame.origin.x, length + 5.0, _feedback.frame.size.width, _feedback.frame.size.height); </code></pre> <p>Using <code>bottomLayoutGuide</code> is exactly like using <code>topLayoutGuide</code>, except the <code>bottomLayoutGuide</code> refers to the lowest vertical extent for content. </p>
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    1. POExample of topLayoutGuide and bottomLayoutGuide UIViewController properties
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    1. USStephen Melvin
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    1. POExample of topLayoutGuide and bottomLayoutGuide UIViewController properties
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    1. COI am setting up AutoLayout in a UIViewController's viewDidLoad. When I run CGFloat length = self.topLayoutGuide.length; I get a value of 0. Where do I implement this message?
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      1. USAveLeon
    2. COtopLayoutGuide is a dynamically generated value. It only makes sense to use it after the view controller's view has been added to the view hierarchy. Using viewDidLoad will cause you to read topLayoutGuide before the view has been added to the view hierarchy and therefore return 0. If you using topLayoutGuide within a subclass of UIViewController, the earliest place you can reliably use it is viewDidLayoutSubviews. If you are using it within a subclass of UIView, you can use layoutSubviews. You can read all about it here: http://goo.gl/Tn6moX
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      1. USStephen Melvin
    3. COI also want to point out that topLayoutGuide will return 0 in some cases, as explained in the documentation. So it's important that you don't read its value too early.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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