支持靠左，居中，靠右，等间距对齐。
靠左等间距.png
居中等间距.png
靠右等间距.png
#import <UIKit/UIKit.h>
typedef NS_ENUM(NSInteger,AlignType){
AlignWithLeft,
AlignWithCenter,
AlignWithRight
};
@interface EqualSpaceFlowLayoutEvolve : UICollectionViewFlowLayout
//两个Cell之间的距离
@property (nonatomic,assign)CGFloat betweenOfCell;
//cell对齐方式
@property (nonatomic,assign)AlignType cellType;
-(instancetype)initWthType : (AlignType)cellType;
@end
#import "EqualSpaceFlowLayoutEvolve.h"
@interface EqualSpaceFlowLayoutEvolve(){
//在居中对齐的时候需要知道这行所有cell的宽度总和
CGFloat _sumWidth ;
}
@end
@implementation EqualSpaceFlowLayoutEvolve
-(instancetype)init{
self = [super init];
if (self){
self.scrollDirection = UICollectionViewScrollDirectionVertical;
self.minimumLineSpacing = 5;
self.minimumInteritemSpacing = 5;
self.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
_betweenOfCell = 5.0;
_cellType = AlignWithLeft;
}
return self;
}
-(instancetype)initWthType:(AlignType)cellType{
self = [super init];
if (self){
self.scrollDirection = UICollectionViewScrollDirectionVertical;
self.minimumLineSpacing = 5;
self.minimumInteritemSpacing = 5;
self.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
_betweenOfCell = 5.0;
_cellType = cellType;
}
return self;
}
-(void)setBetweenOfCell:(CGFloat)betweenOfCell{
_betweenOfCell = betweenOfCell;
self.minimumInteritemSpacing = betweenOfCell;
}
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
NSArray * layoutAttributes_t = [super layoutAttributesForElementsInRect:rect];
NSArray * layoutAttributes = [[NSArray alloc]initWithArray:layoutAttributes_t copyItems:YES];
//用来临时存放一行的Cell数组
NSMutableArray * layoutAttributesTemp = [[NSMutableArray alloc]init];
for (NSUInteger index = 0; index < layoutAttributes.count ; index++) {
UICollectionViewLayoutAttributes *currentAttr = layoutAttributes[index]; // 当前cell的位置信息
UICollectionViewLayoutAttributes *previousAttr = index == 0 ? nil : layoutAttributes[index-1]; // 上一个cell 的位置信
UICollectionViewLayoutAttributes *nextAttr = index + 1 == layoutAttributes.count ?
nil : layoutAttributes[index+1];//下一个cell 位置信息
//加入临时数组
[layoutAttributesTemp addObject:currentAttr];
_sumWidth += currentAttr.frame.size.width;
CGFloat previousY = previousAttr == nil ? 0 : CGRectGetMaxY(previousAttr.frame);
CGFloat currentY = CGRectGetMaxY(currentAttr.frame);
CGFloat nextY = nextAttr == nil ? 0 : CGRectGetMaxY(nextAttr.frame);
//如果当前cell是单独一行
if (currentY != previousY && currentY != nextY){
if ([currentAttr.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {
[layoutAttributesTemp removeAllObjects];
_sumWidth = 0.0;
}else if ([currentAttr.representedElementKind isEqualToString:UICollectionElementKindSectionFooter]){
[layoutAttributesTemp removeAllObjects];
_sumWidth = 0.0;
}else{
[self setCellFrameWith:layoutAttributesTemp];
}
}
//如果下一个不cell在本行，则开始调整Frame位置
else if( currentY != nextY) {
[self setCellFrameWith:layoutAttributesTemp];
}
}
return layoutAttributes;
}
-(void)setCellFrameWith:(NSMutableArray*)layoutAttributes{
CGFloat nowWidth = 0.0;
switch (_cellType) {
case AlignWithLeft:
nowWidth = self.sectionInset.left;
for (UICollectionViewLayoutAttributes * attributes in layoutAttributes) {
CGRect nowFrame = attributes.frame;
nowFrame.origin.x = nowWidth;
attributes.frame = nowFrame;
nowWidth += nowFrame.size.width + self.betweenOfCell;
}
_sumWidth = 0.0;
[layoutAttributes removeAllObjects];
break;
case AlignWithCenter:
nowWidth = (self.collectionView.frame.size.width - _sumWidth - (layoutAttributes.count * _betweenOfCell)) / 2;
for (UICollectionViewLayoutAttributes * attributes in layoutAttributes) {
CGRect nowFrame = attributes.frame;
nowFrame.origin.x = nowWidth;
attributes.frame = nowFrame;
nowWidth += nowFrame.size.width + self.betweenOfCell;
}
_sumWidth = 0.0;
[layoutAttributes removeAllObjects];
break;
case AlignWithRight:
nowWidth = self.collectionView.frame.size.width - self.sectionInset.right;
for (NSInteger index = layoutAttributes.count - 1 ; index >= 0 ; index-- ) {
UICollectionViewLayoutAttributes * attributes = layoutAttributes[index];
CGRect nowFrame = attributes.frame;
nowFrame.origin.x = nowWidth - nowFrame.size.width;
attributes.frame = nowFrame;
nowWidth = nowWidth - nowFrame.size.width - _betweenOfCell;
}
_sumWidth = 0.0;
[layoutAttributes removeAllObjects];
break;
}
}
@end