屏幕快照 2017-01-19 下午4.14.02.png
CircleLayout.h
#import <UIKit/UIKit.h>
@interface CircleLayout : UICollectionViewLayout
@end
CircleLayout.m
#import "CircleLayout.h"
@interface CircleLayout()
/** 布局屬性 */
@property (nonatomic, strong) NSMutableArray *attrsArray;
@end
@implementation XMGCircleLayout
- (NSMutableArray *)attrsArray
{
if (!_attrsArray) {
_attrsArray = [NSMutableArray array];
}
return _attrsArray;
}
- (void)prepareLayout
{
[super prepareLayout];
[self.attrsArray removeAllObjects];
NSInteger count = [self.collectionView numberOfItemsInSection:0];
for (int i = 0; i < count; i++) {
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:indexPath];
[self.attrsArray addObject:attrs];
}
}
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
return self.attrsArray;
}
/**
* 這個(gè)方法需要返回indexPath位置對應(yīng)cell的布局屬性
*/
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
NSInteger count = [self.collectionView numberOfItemsInSection:0];
CGFloat radius = 70;
// 圓心的位置
CGFloat oX = self.collectionView.frame.size.width * 0.5;
CGFloat oY = self.collectionView.frame.size.height * 0.5;
UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
attrs.size = CGSizeMake(50, 50);
if (count == 1) {
attrs.center = CGPointMake(oX, oY);
} else {
CGFloat angle = (2 * M_PI / count) * indexPath.item;
CGFloat centerX = oX + radius * sin(angle);
CGFloat centerY = oY + radius * cos(angle);
attrs.center = CGPointMake(centerX, centerY);
}
return attrs;
}
@end
