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    <p><code>UIView</code> has a <code>clearsContextBeforeDrawing</code> boolean property that switches between the different behaviors you describe. The default is YES which means the view empties the context before calling <code>drawRect:</code></p> <p>Check if that property is set somewhere in the example.</p> <p>Apparently a view doesn't clear it's context correctly, when no backgroundColor is set on the view. Please set backgroundColor to something other than nil.</p> <p>I think this is a bug and have filed <a href="http://openradar.appspot.com/radar?id=444404" rel="nofollow noreferrer">rdar://8165730</a>.</p> <hr> <p>EDIT</p> <p>It's not a bug. You have to set the opaque property to NO or the backgroundColor. The behavior is described in the UIView Documentation.</p> <p>Property <code>clearsContextBeforeDrawing</code>:</p> <blockquote> <p>The default value of this property is YES. When set to YES, the current graphics context buffer in the drawRect: method is automatically cleared to transparent black before drawRect: is invoked. If the view’s opaque property is also set to YES, the backgroundColor property of the view must not be nil or drawing errors may occur.</p> <p>If the value of this property is NO, it is the view’s responsibility to completely fill its content. Drawing performance can be improved if this property is NO—for example, when scrolling.</p> </blockquote> <p>Property <code>opaque</code>:</p> <blockquote> <p>YES if it is opaque; otherwise, NO. If opaque, the drawing operation assumes that the view fills its bounds and can draw more efficiently. The results are unpredictable if opaque and the view doesn’t fill its bounds. Set this property to NO if the view is fully or partially transparent. The default value is YES.</p> </blockquote>
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    1. POQuartz -- sometimes it starts from a blank view and sometimes it doesn't
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    1. COExcellent point . . . but I checked, and the property is set to YES. However, it does not clear.
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      1. USWilliam Jockusch
    2. COAre you calling drawRect: directly? Are you calling setNeedsDisplay on a background thread? Are you calling any UIKit methods or functions on a background thread? Are you doing something with this views layer? If all answers are NO: Try to reduce your code to the bare minimum that's required to reproduce the issue. Only a appDelegate that adds the view to the window and the view calling setNeedsDisplay in touchesEndedWithEvent:
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    3. COShortened code above.
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Guidance
A row detail

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.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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