iOS开发-自定义下拉刷新控件PullDownRefreshView

在开发过程中，有时候需要自定义下拉刷新控件，这时候我们就需要自定义PullDownRefreshView。

PullDownRefreshView是在UIScrollView上。
在这里插入图片描述

一、UIScrollView

在下拉刷新过程中，需要实现UIScrollView的delegate的相关方法

// 拖动过程中

(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView;
(void)scrollViewDidScroll:(UIScrollView *)scrollView;
(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate;

三个方法调用顺序

先执行scrollViewWillBeginDragging:，将要开始拖拽
然后执行n个scrollViewDidScroll，只要是scrollView的contentOffset发生改变就会执行，无论是通过手动拖拽还是代码改变了contentOffset
最后执行scrollViewDidEndDragging:willDecelerate:，拖拽结束，因为没有减速滑动，所以此时也是scrollView最终停止位置

二、实现下拉刷新PullDownRefreshView

在下拉过程中显示，我们需要将refreshView初始化

- (SDPullDownRefreshView *)refreshView {
    if (!_refreshView) {
        _refreshView = [[SDPullDownRefreshView alloc] initWithFrame:CGRectMake(0.0, 0.0, CGRectGetWidth([UIScreen mainScreen].bounds), 80)];
    }
    return _refreshView;
}

1
2
3
4
5
6
7

配置下拉刷新

- (void)configRefresh {
    [self.refreshView setupWithOwner:self.noticationView.tableView delegate:self];
}

1
2
3
4

实现UIScrollView的Delegate的相关方法

- (void)pullDownRefreshDidFinish {
    [self performSelector:@selector(stop) withObject:nil afterDelay:1];
}

- (void)stopLoading {
    [self.refreshView stopLoading];
}

- (void)stop {
    [self stopLoading];
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    [self.refreshView scrollViewWillBeginDragging:scrollView];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    [self.refreshView scrollViewDidScroll:scrollView];
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    [self.refreshView scrollViewDidEndDragging:scrollView willDecelerate:decelerate];
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

整体SDPullDownRefreshView的完整代码

SDPullDownRefreshView.h

#import 

@protocol SDPullDownRefreshViewDelegate;

@interface SDPullDownRefreshView : UIView {
    BOOL isDragging;
    BOOL isLoading;
}

@property (nonatomic, weak) id delegate;
@property (nonatomic, weak) UIScrollView *owner;
@property (nonatomic, strong) UILabel *refreshLabel;
@property (nonatomic, strong) UIActivityIndicatorView *refreshSpinner;

- (void)setupWithOwner:(UIScrollView *)owner delegate:(id)delegate;

- (void)startLoading;
- (void)stopLoading;

// 拖动过程中
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView;
- (void)scrollViewDidScroll:(UIScrollView *)scrollView;
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate;

@end

@protocol SDPullDownRefreshViewDelegate 

- (void)pullDownRefreshDidFinish;

@end

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32

SDPullDownRefreshView.m

#import "SDPullDownRefreshView.h"

#define REFRESH_PULL_UP_STATUS @"下拉可以回到上面"
#define REFRESH_RELEASED_STATUS @"可以松开了"
// 加载中
#define REFRESH_LOADING_STATUS @""
#define REFRESHER_HEIGHT 50.0f

@interface SDPullDownRefreshView ()

@end

@implementation SDPullDownRefreshView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor clearColor];
        
        self.clipsToBounds = YES;
        
        self.refreshLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, REFRESHER_HEIGHT)];
        self.refreshLabel.backgroundColor = [UIColor clearColor];
        self.refreshLabel.font = [UIFont boldSystemFontOfSize:12.0];
        self.refreshLabel.textAlignment = NSTextAlignmentCenter;
        
        self.refreshSpinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
        self.refreshSpinner.frame = CGRectMake((frame.size.width - 20)/2, (REFRESHER_HEIGHT - 20)/2, 20, 20);
        self.refreshSpinner.hidesWhenStopped = YES;
        
        [self addSubview:self.refreshLabel];
        [self addSubview:self.refreshSpinner];
    }
    return self;
}

- (void)layout:(CGPoint)offset {
    if (offset.y < 0) {
        [self setFrame:CGRectMake(0, 0 - REFRESHER_HEIGHT, self.frame.size.width, REFRESHER_HEIGHT)];
        self.refreshLabel.frame = CGRectMake(0, 0, self.frame.size.width, REFRESHER_HEIGHT);
        self.refreshSpinner.frame = CGRectMake((self.frame.size.width - 20)/2, (REFRESHER_HEIGHT - 20)/2, 20, 20);

    } else {
        [self setFrame:CGRectMake(0, -REFRESHER_HEIGHT, self.frame.size.width, 0)];
        self.refreshLabel.frame = CGRectMake(0, 0, self.frame.size.width, REFRESHER_HEIGHT);
        self.refreshSpinner.frame = CGRectMake((self.frame.size.width - 20)/2, (REFRESHER_HEIGHT - 20)/2, 20, 20);
    }
}


- (void)setupWithOwner:(UIScrollView *)owner  delegate:(id)delegate {
    self.owner = owner;
    self.delegate = delegate;
    
    [_owner addSubview:self];
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    if (isLoading) {
        return;
    }
    isDragging = YES;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    
    CGPoint offset = scrollView.contentOffset;
    [self layout:offset];
    
    if (isLoading && offset.y > 0) {
        return;
    }
    
    if (isDragging && offset.y <= 0 ) {
        
        [self.refreshSpinner stopAnimating];
        // Update the arrow direction and label
        if (scrollView.contentOffset.y <= -REFRESHER_HEIGHT) {
            // User is scrolling above the header
            self.refreshLabel.text = REFRESH_RELEASED_STATUS;
        } else {
            // User is scrolling somewhere within the header
            self.refreshLabel.text = REFRESH_PULL_UP_STATUS;
        }
    }
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    if (isLoading) return;
    isDragging = NO;
    
    // 上拉刷新
    if(scrollView.contentOffset.y <= -REFRESHER_HEIGHT){
        [self startLoading];
    }
}


- (void)startLoading
{
    if (isLoading) {
        return;
    }
    isLoading = YES;
    
    UIEdgeInsets contentInset = self.owner.contentInset;
    contentInset.top = REFRESHER_HEIGHT;
    self.refreshLabel.text = REFRESH_LOADING_STATUS;

    [UIView animateWithDuration:0.25 animations:^{
        self.owner.contentInset = contentInset;
        [self.refreshSpinner startAnimating];
    } completion:^(BOOL finished) {
        // Refresh action!
        if ([self.delegate respondsToSelector:@selector(pullDownRefreshDidFinish)]) {
            [self.delegate performSelector:@selector(pullDownRefreshDidFinish) withObject:nil];
        }
    }];
}

- (void)stopLoading {
    isLoading = NO;
    
    UIEdgeInsets contentInset = self.owner.contentInset;
    contentInset.top = 0.0;
    [UIView animateWithDuration:0.15 animations:^{
        self.owner.contentInset = contentInset;
    } completion:^(BOOL finished) {
        
        // Reset the header        
        self.refreshLabel.text = REFRESH_PULL_UP_STATUS;
        
        [self setFrame:CGRectMake(0, -REFRESHER_HEIGHT, self.frame.size.width, 0)];
        [self.refreshSpinner stopAnimating];
    }];
}

@end


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141

三、小结

iOS开发-自定义下拉刷新控件PullDownRefreshView

学习记录，每天不停进步。

相关阅读:
EasyGBS如何解决大屏播放时出现数据未推送情况？
STC51单片机31——红外遥控收发代码
 PC_定点数_模+补码表示+补码相关性质
 UE4 回合游戏项目 18- 退出战斗
 【Pandas】数据分组groupby
Jackson公司蛋白质印迹指南丨样品制备
 LeetCode热题(12.买卖股票的最佳时机)
Git分布式版本控制工具
 vue中this.$set()的用法
 第十四届蓝桥杯模拟赛第二期部分题答案（C++代码）
原文地址：https://blog.csdn.net/gloryFlow/article/details/134059343