Graphics Reference
In-Depth Information
The advantage of this is that you avoid the overhead of constantly creating and releasing
objects (which is expensive because it requires the allocation/deallocation of memory) and
you avoid having to re-apply properties that don't vary between instances.
Let's update our matrix example to use an object pool (see Listing 15.5).
Listing 15.5
Reducing Unnecessary Object Allocation by Recycling
@interface
ViewController
() <UIScrollViewDelegate>
@property
(
nonatomic
,
weak
)
IBOutlet
UIScrollView *scrollView;
@property
(
nonatomic
,
strong
) NSMutableSet *recyclePool;
@end
@implementation
ViewController
- (
void
)viewDidLoad
{
[
super
viewDidLoad
];
//create recycle pool
self
.
recyclePool
= [NSMutableSet
set
];
//set content size
self
.
scrollView
.contentSize =
CGSizeMake
((
WIDTH
-
1
)*
SPACING
,
(
HEIGHT
-
1
)*
SPACING
);
//set up perspective transform
CATransform3D transform = CATransform3DIdentity;
transform.m34 = -
1.0
/
CAMERA_DISTANCE
;
self
.
scrollView
.layer.sublayerTransform = transform;
}
- (
void
)viewDidLayoutSubviews
{
[
self
updateLayers
];
}
- (
void
)scrollViewDidScroll:(UIScrollView *)scrollView
{
[
self
updateLayers
];
}
- (
void
)updateLayers
{
