iOS中怎么实现一个下拉、上拉刷新控件，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
控制器ViewController：
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@end
/*** ---------------分割线--------------- ***/
#import "ViewController.h"
#import "HWRefresh.h"
@interface ViewController ()<UITableViewDataSource, UITableViewDelegate>
@property (nonatomic, strong) NSMutableArray *array;
@property (nonatomic, strong) UITableView *tableView;
@property (nonatomic, assign) NSInteger page;
@end
@implementation ViewController
- (NSMutableArray *)array
{
if (!_array) {
_array = [NSMutableArray array];
}
return _array;
}
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor blackColor];
self.page = 1;
//模拟获取信息
[self getInfo];
//创建控件
[self creatControl];
//添加头部刷新
[self addHeaderRefresh];
//添加尾部刷新
[self addFooterRefresh];
}
- (void)getInfo
{
NSArray *array = @[@"iOS HERO博客", @"iOS HERO博客", @"iOS HERO博客", @"iOS HERO博客", @"http://blog.csdn.net/hero_wqb"];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0f * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
if (self.page == 1) {
self.array = [NSMutableArray arrayWithArray:array];
}else{
[self.array addObjectsFromArray:array];
}
[_tableView reloadData];
[_tableView headerEndRefreshing];
[_tableView footerEndRefreshing];
NSLog(@"已经刷新好了");
});
}
- (void)creatControl
{
//列表视图
_tableView = [[UITableView alloc] initWithFrame:CGRectMake(20, 64, [[UIScreen mainScreen] bounds].size.width - 100, [[UIScreen mainScreen] bounds].size.height - 164) style:UITableViewStylePlain];
_tableView.dataSource = self;
_tableView.delegate = self;
[self.view addSubview:_tableView];
}
- (void)addHeaderRefresh
{
__weak typeof(self) weakSelf = self;
[_tableView addHeaderRefreshWithCallback:^{
__strong typeof(weakSelf) strongSelf = weakSelf;
strongSelf.page = 1;
[strongSelf getInfo];
}];
}
- (void)addFooterRefresh
{
__weak typeof(self) weakSelf = self;
[_tableView addFooterRefreshWithCallback:^{
__strong typeof(weakSelf) strongSelf = weakSelf;
strongSelf.page ++;
[strongSelf getInfo];
}];
}
#pragma mark - UITableViewDataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return self.array.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *identifier = @"refreshTest";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
if (!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
}
cell.textLabel.text = [_array[indexPath.row] stringByAppendingString:[NSString stringWithFormat:@"_%ld", indexPath.row]];
return cell;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
//滑动到底部自动刷新
if (_tableView.contentSize.height > _tableView.frame.size.height && _tableView.contentOffset.y + _tableView.frame.size.height > _tableView.contentSize.height - 40 && _page < 50) {
[_tableView footerBeginRefreshing];
}
}
@end刷新基类HWRefreshBaseView：
#import <UIKit/UIKit.h>
#define HWRefreshContentOffset @"contentOffset"
typedef enum {
HWRefreshStateNormal = 0, //普通状态
HWRefreshStatePulling, //释放即可刷新的状态
HWRefreshStateRefreshing, //正在刷新中的状态
} HWRefreshState;
@interface HWRefreshBaseView : UIView
@property (nonatomic, weak) UIScrollView *scrollView;
@property (nonatomic, copy) NSString *pullToRefreshText;
@property (nonatomic, copy) NSString *releaseToRefreshText;
@property (nonatomic, copy) NSString *refreshingText;
@property (nonatomic, copy) void (^refreshingCallback)();
@property (nonatomic, assign) HWRefreshState state;
@property (nonatomic, assign) UIEdgeInsets scrollViewOriginalInset;
- (void)beginRefreshing;
- (void)endRefreshing;
@end
/*** ---------------分割线--------------- ***/
#import "HWRefreshBaseView.h"
#define KHWRefreshViewHeight 44.0f
#define KImageW 30.0f
#define KLabelW 100.0f
@interface HWRefreshBaseView ()
@property (nonatomic, weak) UILabel *rLabel;
@property (nonatomic, weak) UIImageView *rImageView;
@end
@implementation HWRefreshBaseView
- (instancetype)initWithFrame:(CGRect)frame
{
frame.size.height = KHWRefreshViewHeight;
if (self = [super initWithFrame:frame]) {
CGFloat imageH = 30.f;
CGFloat labelH = 20.f;
CGFloat imageX = ([UIScreen mainScreen].bounds.size.width - KImageW - KLabelW) * 0.5;
CGFloat imageY = (KHWRefreshViewHeight - imageH) * 0.5;
CGFloat labelY = (KHWRefreshViewHeight - labelH) * 0.5;
//图片
UIImageView *rImageView = [[UIImageView alloc] initWithFrame:CGRectMake(imageX, imageY, KImageW, imageH)];
rImageView.image = [UIImage imageNamed:@"refreshing.jpg"];
[self addSubview:rImageView];
self.rImageView = rImageView;
//标签
UILabel *rLabel = [[UILabel alloc] initWithFrame:CGRectMake(CGRectGetMaxX(rImageView.frame), labelY, KLabelW, labelH)];
rLabel.text = self.pullToRefreshText;
rLabel.font = [UIFont systemFontOfSize:14.0f];
rLabel.textAlignment = NSTextAlignmentCenter;
[self addSubview:rLabel];
self.rLabel = rLabel;
}
return self;
}
- (void)willMoveToSuperview:(UIView *)newSuperview
{
[super willMoveToSuperview:newSuperview];
//旧的父控件
[self.superview removeObserver:self forKeyPath:HWRefreshContentOffset context:nil];
//新的父控件
if (newSuperview) {
[newSuperview addObserver:self forKeyPath:HWRefreshContentOffset options:NSKeyValueObservingOptionNew context:nil];
//记录UIScrollView
_scrollView = (UIScrollView *)newSuperview;
//记录UIScrollView最开始的contentInset
_scrollViewOriginalInset = _scrollView.contentInset;
}
//居中显示图片、提示信息
CGRect temFrame = _rImageView.frame;
temFrame.origin.x = (newSuperview.frame.size.width - KImageW - KLabelW) * 0.5;
_rImageView.frame = temFrame;
CGRect tf = _rLabel.frame;
tf.origin.x = CGRectGetMaxX(_rImageView.frame);
_rLabel.frame = tf;
}
- (void)setPullToRefreshText:(NSString *)pullToRefreshText
{
_pullToRefreshText = pullToRefreshText;
self.rLabel.text = pullToRefreshText;
}
- (void)setState:(HWRefreshState)state
{
if (_state == state) return;
switch (state) {
case HWRefreshStateNormal: {
[self stopAnimating];
self.rLabel.text = self.pullToRefreshText;
break;
}
case HWRefreshStatePulling: {
self.rLabel.text = self.releaseToRefreshText;
break;
}
case HWRefreshStateRefreshing: {
[self startAnimating];
self.rLabel.text = self.refreshingText;
if (self.refreshingCallback) self.refreshingCallback();
break;
}
default:
break;
}
_state = state;
}
//开始刷新
- (void)beginRefreshing
{
self.state = HWRefreshStateRefreshing;
}
//结束刷新
- (void)endRefreshing
{
self.state = HWRefreshStateNormal;
}
//开始动画
- (void)startAnimating
{
NSMutableArray *array = [NSMutableArray array];
for (int i = 0; i < 2; i++) {
NSString *imageName = [NSString stringWithFormat:@"refreshing%02d.jpg", i + 1];
UIImage *image = [UIImage imageNamed:imageName];
[array addObject:image];
}
[_rImageView setAnimationImages:array];
[_rImageView setAnimationDuration:0.3f];
[_rImageView startAnimating];
}
//结束动画
- (void)stopAnimating
{
if (_rImageView.isAnimating) {
[_rImageView stopAnimating];
[_rImageView performSelector:@selector(setAnimationImages:) withObject:nil afterDelay:0];
}
}
@end头部刷新HWRefreshHeader：
#import "HWRefreshBaseView.h"
@interface HWRefreshHeader : HWRefreshBaseView
+ (instancetype)header;
@end
/*** ---------------分割线--------------- ***/
#import "HWRefreshHeader.h"
@implementation HWRefreshHeader
+ (instancetype)header
{
return [[HWRefreshHeader alloc] init];
}
- (instancetype)initWithFrame:(CGRect)frame
{
if (self = [super initWithFrame:frame]) {
self.pullToRefreshText = @"下拉即可刷新";
self.releaseToRefreshText = @"释放即可刷新";
self.refreshingText = @"刷新中...";
}
return self;
}
- (void)willMoveToSuperview:(UIView *)newSuperview
{
[super willMoveToSuperview:newSuperview];
//设置自己的位置和尺寸
CGRect frame = self.frame;
frame.origin.y = - self.frame.size.height;
self.frame = frame;
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
//不能跟用户交互或正在刷新就直接返回
if (!self.userInteractionEnabled || self.alpha <= 0.01 || self.hidden || self.state == HWRefreshStateRefreshing) return;
//根据偏移量设置相应状态
if ([keyPath isEqualToString:HWRefreshContentOffset]) {
[self setStateWithContentOffset];
}
}
- (void)setStateWithContentOffset
{
//当前的contentOffset
CGFloat currentOffsetY = self.scrollView.contentOffset.y;
//头部控件刚好出现的offsetY
CGFloat happenOffsetY = - self.scrollViewOriginalInset.top;
//如果是向上滚动到看不见头部控件，直接返回
if (currentOffsetY >= happenOffsetY) return;
//滑动时
if (self.scrollView.isDragging) {
//普通状态和即将刷新状态的临界点
CGFloat normalTopullingOffsetY = happenOffsetY - self.frame.size.height;
//转为即将刷新状态
if (self.state == HWRefreshStateNormal && currentOffsetY < normalTopullingOffsetY) {
self.state = HWRefreshStatePulling;
//转为普通状态
}else if (self.state == HWRefreshStatePulling && currentOffsetY >= normalTopullingOffsetY) {
self.state = HWRefreshStateNormal;
}
//松手时，如果是松开就可以进行刷新的状态，则进行刷新
}else if (self.state == HWRefreshStatePulling) {
self.state = HWRefreshStateRefreshing;
}
}
- (void)setState:(HWRefreshState)state
{
//若状态未改变，直接返回
if (self.state == state) return;
//保存旧状态
HWRefreshState oldState = self.state;
//调用父类方法
[super setState:state];
switch (state) {
case HWRefreshStateNormal: {
//如果由刷新状态返回到普通状态
if (oldState == HWRefreshStateRefreshing) {
[UIView animateWithDuration:0.25f animations:^{
UIEdgeInsets inset = self.scrollView.contentInset;
inset.top -= self.frame.size.height;
self.scrollView.contentInset = inset;
}];
}
break;
}
case HWRefreshStatePulling: {
break;
}
case HWRefreshStateRefreshing: {
//执行动画
[UIView animateWithDuration:0.25f animations:^{
CGFloat top = self.scrollViewOriginalInset.top + self.frame.size.height;
//增加滚动区域
UIEdgeInsets inset = self.scrollView.contentInset;
inset.top = top;
self.scrollView.contentInset = inset;
//设置滚动位置
CGPoint offset = self.scrollView.contentOffset;
offset.y = - top;
self.scrollView.contentOffset = offset;
}];
break;
}
default:
break;
}
self.state = state;
}
@end分类UIScrollView+HWRefresh：
#import <UIKit/UIKit.h>
@interface UIScrollView (HWRefresh)
//添加下拉刷新回调
- (void)addHeaderRefreshWithCallback:(void (^)())callback;
//让下拉刷新控件停止刷新
- (void)headerEndRefreshing;
//添加上拉刷新回调
- (void)addFooterRefreshWithCallback:(void (^)())callback;
//让上拉刷新控件开始刷新
- (void)footerBeginRefreshing;
//让上拉刷新控件停止刷新
- (void)footerEndRefreshing;
@end
/*** ---------------分割线--------------- ***/
#import "UIScrollView+HWRefresh.h"
#import "HWRefreshHeader.h"
#import "HWRefreshFooter.h"
#import <objc/runtime.h>
@interface UIScrollView ()
@property (nonatomic, weak) HWRefreshHeader *header;
@property (weak, nonatomic) HWRefreshFooter *footer;
@end
@implementation UIScrollView (HWRefresh)
static char HWRefreshHeaderKey;
static char HWRefreshFooterKey;
- (void)setHeader:(HWRefreshHeader *)header
{
[self willChangeValueForKey:@"HWRefreshHeaderKey"];
objc_setAssociatedObject(self, &HWRefreshHeaderKey, header, OBJC_ASSOCIATION_ASSIGN);
[self didChangeValueForKey:@"HWRefreshHeaderKey"];
}
- (HWRefreshHeader *)header
{
return objc_getAssociatedObject(self, &HWRefreshHeaderKey);
}
- (void)setFooter:(HWRefreshFooter *)footer
{
[self willChangeValueForKey:@"HWRefreshFooterKey"];
objc_setAssociatedObject(self, &HWRefreshFooterKey, footer, OBJC_ASSOCIATION_ASSIGN);
[self didChangeValueForKey:@"HWRefreshFooterKey"];
}
- (HWRefreshFooter *)footer
{
return objc_getAssociatedObject(self, &HWRefreshFooterKey);
}
- (void)addHeaderRefreshWithCallback:(void (^)())callback
{
if (!self.header) {
HWRefreshHeader *header = [HWRefreshHeader header];
[self addSubview:header];
self.header = header;
}
self.header.refreshingCallback = callback;
}
- (void)headerEndRefreshing
{
[self.header endRefreshing];
}
- (void)addFooterRefreshWithCallback:(void (^)())callback
{
if (!self.footer) {
HWRefreshFooter *footer = [HWRefreshFooter footer];
[self addSubview:footer];
self.footer = footer;
}
self.footer.refreshingCallback = callback;
}
- (void)footerBeginRefreshing
{
[self.footer beginRefreshing];
}
- (void)footerEndRefreshing
{
[self.footer endRefreshing];
}
@end看完上述内容，你们掌握iOS中怎么实现一个下拉、上拉刷新控件的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注亿速云行业资讯频道，感谢各位的阅读！
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