Significantly improves AZTableViewCell speed.

 - Shadow users should manipulate the tableViewBackgroundColor property.
 - Refactors drawing code, fixes numerous bugs
 - Cell backgrounds are often opaque, and no longer overlap by design.
 - Drawing code are now (internal) functions for future use.
 - Bugs fixed which caused needless image creation and cache filling

AZAppearanceKit/AZTableViewCell.h

@@ -4,7 +4,7 @@
 //
 //  Created by Victor Pena Placer on 2/28/12.
 //  Copyright (c) 2012 Victor Pena Placer. All rights reserved.
-//  Copyright (c) 2012 Alexsander Akers & Zachary Waldowski. All rights reserved.
+//  Copyright (c) 2012-2013 Alexsander Akers & Zachary Waldowski. All rights reserved.
 //
 
 #import <UIKit/UIKit.h>
@@ -14,44 +14,57 @@
 
 /** `AZTableViewCell` is a subclass of `UITableViewCell`, and is
  compatible with any `UITableView`.
- 
- `AZTableViewCell` adds a set of customizations such as corner radius, 
+
+ `AZTableViewCell` adds a set of customizations such as corner radius,
  shadow, background gradient, and selection gradient.
- 
+
  ### Using it
- 
+
  In your `dataSource`'s `-tableView:cellForRowAtIndexPath:`, change all
  references to `UITableViewCell` to `AZTableViewCell`.
- 
+
+ #### Performance considerations
+
+ One tip that will get you very far with iOS graphics programming:
+ alpha blending is slow. If you intend for a cell to have a shadow,
+ *set the background color*. The resulting cell will be opaque, and
+ composite onto screen extremely quickly.
+
+ Normally, this also implies that the table view and cells must use
+ the same solid background color - hey, it's flat UI design! However,
+ the `UIColor` pattern system and pattern phase might still allow
+ textured backgrounds.
+
  ### Customizing appearance
- 
+
  Cells are compatible with both grouped and plain tables, though they
  generally look better in grouped tables.
- 
+
  #### Grouped tables
- 
+
  You can change the cell's appearance as follows:
- 
+
  - cell's drop shadow color (border will be disabled when set).
- - cell's background color or gradient.
+ - cell's opaque background color (for when a shadow is used).
+ - cell's fill color (using `backgroundColor`) or gradient.
  - cell's border color (ignored when the shadow color is set).
  - cell's corner radius.
  - cell's separator color.
  - cell's selection gradient.
- 
+
  #### Plain tables
- 
+
  You can change the cell's appearance as follows:
- 
- - cell's background color or gradient.
+
+ - cell's fill color (using `backgroundColor`) or gradient.
  - cell's separator.
- - cell's selection gradient. 
+ - cell's selection gradient.
  */
 @interface AZTableViewCell : UITableViewCell <UIAppearance>
 
 /** @name Customizing appearance */
 
- /** Specifies the shadow used to draw a shadow for the table view cell.
+/** Specifies the shadow used to draw a shadow for the table view cell.
 
  By default, this is a shadow with a vertical offset of 1 point, a black color
  with an alpha of 0.7, and a blur radius of 3 points.
@@ -60,39 +73,50 @@
 @property (nonatomic, strong) id <AZShadow> shadow;
 
 /** Specifies the gradient used when the cell is not selected.
- 
+
  By default, this is `nil`, yielding a white background.
- 
+
  */
 @property (nonatomic, strong) AZGradient *gradient;
 
+/** Specifies the color for the shadowed extremities of the cell.
+ This should match the background color of the table view the
+ cell is contained in.
+
+ By default, this is `nil`, leading to reduced table view performance.
+
+ This property is ignored when no shadow is set;
+
+ */
+@property (nonatomic, strong) UIColor *tableViewBackgroundColor;
+
 /** Specifies the gradient used when the cell is selected.
- 
+
  By default, this is made up of blue tones.
- 
+
  */
 @property (nonatomic, strong) AZGradient *selectionGradient;
 
-/** Specifies the color used for the cell's border. 
- 
+/** Specifies the color used for the cell's border.
+
  If shadowColor has a value, borderColor will be ignored.
- 
+
  This property has a gray color by default.
- 
+
  */
 @property (nonatomic, strong) UIColor *borderColor;
 
 /** Specifies the radius used for the cell's corners.
- 
+
  By default it is set to 8.
- 
+
  */
 @property (nonatomic, assign) float cornerRadius;
 
 /** Specifies the color used for the cell's separator line.
- 
+
  This property has a light gray color by default.
- 
+
  */
 @property (nonatomic, strong) UIColor *separatorColor;