本文实例为大家分享了iOS实现列表下拉放大效果展示的具体代码，供大家参考，具体内容如下
先看效果图
突然发现没有做出来之前都觉得蛮难的，做出来之后就觉得So Easy 大家都有这样的感触吧
做这个就重写 UICollectionViewFlowLayout 的几个方法就可以
OC版本
创建一个类 CustomCollectionViewFlowLayout 继承 UICollectionViewFlowLayout
//// CustomCollectionViewFlowLayout.m// //// Created by GongHui_YJ on 16/8/4.// Copyright ©
2016年 Yangjian. All rights reserved.//#import "CustomCollectionViewFlowLayout.h"@implementation CustomCollectionViewFlowLayout- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds{
return YES;
}
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
UICollectionView *collectionView = [self collectionView];
UIEdgeInsets insets = [collectionView contentInset];
CGPoint offset = [collectionView contentOffset];
CGFloat minY = -insets.top;
NSArray *attributes = [super layoutAttributesForElementsInRect:rect];
if (offset.y < minY) {
CGSize headerSize = [self headerReferenceSize];
CGFloat deltaY = fabsf(offset.y - minY);
for (UICollectionViewLayoutAttributes *attrs in attributes) {
if ([attrs representedElementKind] == UICollectionElementKindSectionHeader) {
CGRect headerRect = [attrs frame];
headerRect.size.height = MAX(minY, headerSize.height + deltaY);
headerRect.origin.y = headerRect.origin.y - deltaY;
[attrs setFrame:headerRect];
break;
}
}
}
return attributes;
}
@end
在控制器中使用 先导入头文件
// 创建collectionView CustomCollectionViewFlowLayout *flowLayout=[[CustomCollectionViewFlowLayout alloc] init];
[flowLayout setSectionInset:UIEdgeInsetsMake(0, 0, 10, 0)];
[flowLayout setItemSize:CGSizeMake(kScreenWidth / collectionCellW, kScreenWidth / collectionCellW)];
[flowLayout setHeaderReferenceSize:CGSizeMake(kScreenWidth, userInfoImageViewH)];
[flowLayout setFooterReferenceSize:CGSizeMake(kScreenWidth, 83)];
[flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
[flowLayout setMinimumInteritemSpacing:0.0];
[flowLayout setMinimumLineSpacing:0.0];
self.homeCollectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, kScreenWidth, kScreenHeight - 44)collectionViewLayout:flowLayout];
self.homeCollectionView.backgroundColor = kViewBackgroundColor;
self.homeCollectionView.alwaysBounceVertical = YES;
self.homeCollectionView.showsVerticalScrollIndicator = NO;
//设置代理 self.homeCollectionView.delegate = self;
self.homeCollectionView.dataSource = self;
[self.view addSubview:self.homeCollectionView];
// 注册表头 [self.homeCollectionView registerClass:[YJHeaderCollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:kCollectionHeaderView];
// 注册表尾 [self.homeCollectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:kCollectionFooterView];
Swift版
喜欢swift 不需要导入头文件那么麻烦
//// CustomCollectionViewFlowLayout.swift// //// Created by GongHui_YJ on 16/8/4.// Copyright ©
2016年YangJian. All rights reserved.//import UIKitclass CustomCollectionViewFlowLayout: UICollectionViewFlowLayout {
override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
return true }
override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
let collectionView = self.collectionView let insets = collectionView?.contentInset let offset = collectionView?.contentOffset let minY = -((insets?.top)!) let attributesArray = super.layoutAttributesForElementsInRect(rect) if offset!.y < minY {
let headerSize = self.headerReferenceSize let deltaY = CGFloat(fabsf(Float((offset?.y)! - CGFloat(minY)))) for attrs:UICollectionViewLayoutAttributes in attributesArray! {
if attrs.representedElementKind == UICollectionElementKindSectionHeader {
var headerRect = attrs.frame headerRect.size.height = max(minY, headerSize.height + deltaY) headerRect.origin.y = headerRect.origin.y - deltaY attrs.frame = headerRect break }
}
}
return attributesArray }
}
在控制器 viewDidLoad方法实现
let customFlowLayout = CustomCollectionViewFlowLayout() customFlowLayout.headerReferenceSize = CGSizeMake(kScreenWidth, 203) customFlowLayout.footerReferenceSize = CGSizeMake(kScreenWidth, 83) customFlowLayout.minimumInteritemSpacing = 0 customFlowLayout.minimumLineSpacing = 0 customFlowLayout.itemSize = CGSizeMake(kScreenWidth / 3.000006, kScreenWidth / 3.00006) customFlowLayout.sectionInset = UIEdgeInsetsMake(0, 0, 10, 0) self.homeCollectionView.setCollectionViewLayout(customFlowLayout, animated: true) self.homeCollectionView.backgroundColor = kViewBackgroundColor self.homeCollectionView.alwaysBounceVertical = true let nib = UINib(nibName: "CommonCollectionViewCell", bundle: nil) self.homeCollectionView.registerNib(nib, forCellWithReuseIdentifier: cellId) // 注册表头表尾 let headerNib = UINib(nibName: "HeaderCollectionReusableView", bundle: nil) self.homeCollectionView.registerNib(headerNib, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: collectionHeaderId) self.homeCollectionView.registerClass(UICollectionReusableView.classForCoder(), forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withReuseIdentifier: collectionFooterId)
注：不要实现UICollectionViewDelegateFlowLayout的代理方法了。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
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