UITableView 上拉刷新控件

.h 文件

#import <UIKit/UIKit.h>

@protocol RefreshTableFooterViewDelegate;
@interface RefreshTableFooterView : UIView
@property (nonatomic, weak) id<RefreshTableFooterViewDelegate> delegate;

// 实现ScrollViewDelegate 后在对应的 didEndingDragging 方法中调用
-(void)refreshFooterScrollViewDidEndDragging:(UIScrollView *)scrollView;

// 在重新刷新 tableView 后调用
-(void)refreshFooterViewDataSourceDidFinishedLoading:(UIScrollView*)scrollView;

// 在重新刷新 tableView 之前调用
-(void)refreshFooterViewShouldBeHiddenBeforeDataSourceReloadNewData;
@end

@protocol RefreshTableFooterViewDelegate <NSObject>

-(void)refreshTableFooterViewTriggerRefresh;
-(BOOL)refreshTableFooterViewIsLoading;
-(BOOL)refreshTableFooterViewHasMore;

@end

.m 文件

#import "RefreshTableFooterView.h"

@implementation RefreshTableFooterView
{
    UIActivityIndicatorView *_indicatorView;
    UILabel *_descriptionLabel;
    BOOL _isLastPage;
    BOOL _hasRefreshed;
}

-(instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        CGFloat yAxis = 3;
        CGFloat width = 200;
        
        _indicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
        _indicatorView.frame = CGRectMake((CGRectGetWidth(self.bounds) - 200)/2 - CGRectGetWidth(_indicatorView.bounds), yAxis, CGRectGetWidth(_indicatorView.bounds), CGRectGetHeight(_indicatorView.bounds));
        _indicatorView.hidesWhenStopped = YES;
        [self addSubview:_indicatorView];
        [_indicatorView stopAnimating];
        
        _descriptionLabel = [[UILabel alloc] initWithFrame:CGRectMake((CGRectGetWidth(self.bounds) - 200)/2, yAxis, width, CGRectGetHeight(_indicatorView.bounds))];
        _descriptionLabel.text = @"上拉刷新";
        _descriptionLabel.textAlignment = NSTextAlignmentCenter;
        _descriptionLabel.textColor = [UIColor lightGrayColor];
        [self addSubview:_descriptionLabel];
    }
    return self;
}

-(void)refreshFooterScrollViewDidEndDragging:(UIScrollView *)scrollView
{
    if (!self.delegate ||
        ![self.delegate respondsToSelector:@selector(refreshTableFooterViewIsLoading)] ||
        [self.delegate refreshTableFooterViewIsLoading]) {
        return;
    }
    
    if (![self.delegate refreshTableFooterViewHasMore]) {
        _descriptionLabel.text = @"已经加载所有~";
        return;
    }
    
    CGFloat contentHeight = scrollView.contentSize.height;
    CGFloat offsetY = scrollView.contentOffset.y;
    CGFloat containerHeight = scrollView.bounds.size.height;
    BOOL refreshOrNot = containerHeight + offsetY > contentHeight - 0;
    if (refreshOrNot && [self.delegate respondsToSelector:@selector(refreshTableFooterViewTriggerRefresh)]) {
        [self.delegate refreshTableFooterViewTriggerRefresh];
        _descriptionLabel.text = @"加载中...";
        _indicatorView.hidden = NO;
        [_indicatorView startAnimating];
        [scrollView setContentInset:UIEdgeInsetsMake(.0, 50.0, .0, .0)];
    }
}

-(void)refreshFooterViewShouldBeHiddenBeforeDataSourceReloadNewData {
    self.hidden = YES;
}

-(void) refreshFooterViewDataSourceDidFinishedLoading:(UIScrollView *)scrollView {
    [scrollView setContentInset:UIEdgeInsetsMake(.0, .0, .0, .0)];
    CGRect original = self.frame;
    original.origin.y = scrollView.contentSize.height > scrollView.bounds.size.height ? scrollView.contentSize.height : scrollView.bounds.size.height;
    self.frame = original;
    self.hidden = NO;
    [_indicatorView stopAnimating];
    _descriptionLabel.text = @"上拉刷新";
}


@end