ios UICollectionView的使用

UICollectionView的使用有两种方法，一种是继承UICollectionViewController，这个Controller会自带一个UICollectionView；另外一种是作为一个视图放在普通的UIViewController里面。

个人更喜欢第二种。下面采用第二种方式简单介绍一下UICollectionView的使用。

1.UIViewController实现委托，代码如下

@interface YourViewController : UIViewController<UICollectionViewDataSource,UICollectionViewDelegate>

2.声明UICollectionView，代码如下

@property(nonatomic,retain)UICollectionView*myCollectionView;

3.初始化UICollectionView，代码如下

- (void)viewDidLoad

{

[super viewDidLoad];

[self initConllectionView];

}

-(void)initConllectionView{

CircleLayout*layout=[[CircleLayout alloc] init];

myCollectionView=[[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];

[myCollectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cell"];

myCollectionView.backgroundColor=[UIColor whiteColor];

myCollectionView.delegate=self;

myCollectionView.dataSource=self;

[self.view addSubview:myCollectionView];

[layout release];

}

这里面的CircleLayout继承自UICollectionViewLayout，主要用来表现UICollectionView的布局以及一些属性。

4.实现- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath;

-(UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{

UICollectionViewCell*cell=[collectionView dequeueReusableCellWithReuseIdentifier:CELL_STR forIndexPath:indexPath];

for (UIView*view in cell.contentView.subviews) {

if (view) {

[view removeFromSuperview];

}

}

UIImageView*imgView=[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, ITEM_WIDTH, ITEM_WIDTH)];

if (indexPath.row>4) {

imgView.image=[UIImage imageNamed:@"apple.png"];

}else{

imgView.image=[UIImage imageNamed:@"applec.png"];

}

[cell.contentView addSubview:imgView];

[imgView release];

return cell;

}

5.cell的大小

-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{

return CGSizeMake(130,130);

}

CircleLayout的代码：

CircleLayout.h

#import <UIKit/UIKit.h>

#import <QuartzCore/QuartzCore.h>

@interface CircleLayout : UICollectionViewLayout

@property (nonatomic, assign) CGPoint center;

@property (nonatomic, assign) CGFloat radius;

@property (nonatomic, assign) NSInteger cellCount;

@end

CircleLayout.m

#define ITEM_SIZE 130

#import "CircleLayout.h"

@implementation CircleLayout

@synthesize cellCount,center,radius;

- (void)prepareLayout{

[super prepareLayout];

CGSize size = self.collectionView.frame.size;

cellCount=[self.collectionView numberOfItemsInSection:0];

center=CGPointMake(size.width/2, size.height/2);

radius = MIN(size.width, size.height) / 2.5;

}

-(CGSize)collectionViewContentSize{

return [self collectionView].frame.size;

}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)path

{

UICollectionViewLayoutAttributes* attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:path];

attributes.size = CGSizeMake(ITEM_SIZE, ITEM_SIZE);

attributes.center = CGPointMake(center.x + radius * cosf(2 * path.item * M_PI /cellCount),

center.y + radius * sinf(2 * path.item * M_PI /cellCount));

return attributes;

}

-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect{

NSMutableArray* attributes = [NSMutableArray array];

for (NSInteger i=0 ; i < self.cellCount; i++) {

NSIndexPath* indexPath = [NSIndexPath indexPathForItem:i inSection:0];

[attributes addObject:[self layoutAttributesForItemAtIndexPath:indexPath]];

}

return attributes;

}

- (UICollectionViewLayoutAttributes *)initialLayoutAttributesForInsertedItemAtIndexPath:(NSIndexPath *)itemIndexPath{

UICollectionViewLayoutAttributes* attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath];

attributes.alpha = 0.0;

attributes.center = CGPointMake(center.x, center.y);

return attributes;

}

- (UICollectionViewLayoutAttributes *)finalLayoutAttributesForDeletedItemAtIndexPath:(NSIndexPath *)itemIndexPath

{

UICollectionViewLayoutAttributes* attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath];

attributes.alpha = 0.0;

attributes.center = CGPointMake(center.x, center.y);

attributes.transform3D = CATransform3DMakeScale(0.1, 0.1, 1.0);

return attributes;

}

@end