iOS开发-Lottie实现下拉刷新动画效果

在开发过程中，有时候需要自定义下拉刷新控件，这里使用Lottie实现下拉刷新动画效果。

一、Lottie

Lottie 是一个应用十分广泛动画库，适用于Android、iOS、Web、ReactNative、Windows的库，它解析了用Bodymovin导出为json的Adobe After Effects动画，并在移动和网络上进行了原生渲染。

Lottie方法方案是由设计师出动画，导出为json，给前端、iOS、Android播放。

在iOS开发中，我们需要使用lottie-ios库，在podfile中引入库

pod ‘lottie-ios’, ‘~> 2.5.3’

可以使用LOTAnimationView来进行动画播放。

二、LOTAnimationView播放动画

比如我们有一个loading_header，如图

使用LOTAnimationView来进行播放动画

- (LOTAnimationView *)animationView {
    if (!_animationView) {
        _animationView = [[LOTAnimationView alloc] initWithFrame:CGRectZero];
        _animationView.backgroundColor = [UIColor clearColor];
        _animationView.frame = CGRectMake(0.0, 0.0, kAnimationSize, kAnimationSize);
        _animationView.loopAnimation = YES;
        [_animationView setAnimationNamed:@"loading_header"];
    }
    return _animationView;
}

播放动画

- (void)startAnimation {
    [self.animationView play];
}

停止动画播放

- (void)stopAnimation {
    [self.animationView stop];
}

完整代码如下

INRefreshGifLoadingView.h

#import <UIKit/UIKit.h>

@interface INRefreshGifLoadingView : UIView

- (void)displayIndicator:(CGFloat)precent;

- (void)startAnimation;

- (void)stopAnimation;

@end

INRefreshGifLoadingView.m

#import "INRefreshGifLoadingView.h"
#import <Lottie/Lottie.h>

#import "UIColor+Addition.h"
#import "UIImageView+WebCache.h"

static CGFloat kAnimationSize = 60.0;

@interface INRefreshGifLoadingView ()

@property (nonatomic, strong) LOTAnimationView *animationView;

@end

@implementation INRefreshGifLoadingView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self addSubview:self.animationView];
        [self layoutFrame];
    }
    return self;
}

- (void)layoutFrame {
    self.animationView.center = self.center;
}

#pragma mark - Display
- (void)displayIndicator:(CGFloat)precent {
    
}

- (void)startAnimation {
    [self.animationView play];
}

- (void)stopAnimation {
    [self.animationView stop];
}

#pragma mark - SETTER/GETTER
- (LOTAnimationView *)animationView {
    if (!_animationView) {
        _animationView = [[LOTAnimationView alloc] initWithFrame:CGRectZero];
        _animationView.backgroundColor = [UIColor clearColor];
        _animationView.frame = CGRectMake(0.0, 0.0, kAnimationSize, kAnimationSize);
        _animationView.loopAnimation = YES;
        [_animationView setAnimationNamed:@"loading_header"];
    }
    return _animationView;
}

@end

三、使用MJRefresh进行下拉刷新播放

在使用MJRefresh时候，我们继承MJRefreshStateHeader来实现lottie动画播放效果。

根据MJRefreshState来进行控制动画是否播放

完整代码如下

INRefreshHeader.h

#import "MJRefresh.h"
#import "INRefreshGifLoadingView.h"

@interface INRefreshHeader : MJRefreshStateHeader

@property (nonatomic, assign) BOOL showInsetTop;

@property (nonatomic, strong) INRefreshGifLoadingView *gifLoadingView;

@end

INRefreshHeader.m

#import "INRefreshHeader.h"

@implementation INRefreshHeader

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.lastUpdatedTimeLabel.hidden = YES;
        self.stateLabel.hidden = YES;
        [self addSubview:self.gifLoadingView];
    }
    return self;
}

- (INRefreshGifLoadingView *)gifLoadingView {
    if (!_gifLoadingView) {
        _gifLoadingView = [[INRefreshGifLoadingView alloc] initWithFrame:CGRectMake(0.0, 0.0, CGRectGetWidth([UIScreen mainScreen].bounds), self.bounds.size.height)];
    }
    return _gifLoadingView;
}

- (void)setState:(MJRefreshState)state {
    MJRefreshCheckState
    
    // 根据状态做事情
    if (state == MJRefreshStateIdle) {
        if (oldState == MJRefreshStateRefreshing) {
            self.gifLoadingView.alpha = 1.0;

            // 如果执行完动画发现不是idle状态，就直接返回，进入其他状态
            if (self.state != MJRefreshStateIdle) return;
            
            
            self.gifLoadingView.alpha = 1.0;

            
            [self.gifLoadingView stopAnimation];

        } else {
            
            [self.gifLoadingView stopAnimation];

        }
    } else if (state == MJRefreshStatePulling) {
        
        [self.gifLoadingView stopAnimation];

    } else if (state == MJRefreshStateRefreshing) {
        
        [self.gifLoadingView startAnimation];
    }
}

- (void)prepare {
    [super prepare];
    self.mj_h = 70.0;
}

- (void)placeSubviews {
    [super placeSubviews];
    
    CGFloat centerX = self.mj_w * 0.5;
    CGFloat centerY = self.mj_h * 0.5;
    
    self.gifLoadingView.center = CGPointMake(centerX, centerY);
}

/** 当scrollView的contentOffset发生改变的时候调用 */
- (void)scrollViewContentOffsetDidChange:(NSDictionary *)change {
    [super scrollViewContentOffsetDidChange:change];
    NSLog(@"change:%@",change);
    
    CGPoint old = [change[@"old"] CGPointValue];
    CGPoint new = [change[@"new"] CGPointValue];
    
    CGFloat precent = -new.y/self.mj_h;
    
    [self.gifLoadingView displayIndicator:precent];
}

/** 当scrollView的contentSize发生改变的时候调用 */
- (void)scrollViewContentSizeDidChange:(NSDictionary *)change {
    [super scrollViewContentSizeDidChange:change];
}

/** 当scrollView的拖拽状态发生改变的时候调用 */
- (void)scrollViewPanStateDidChange:(NSDictionary *)change {
    [super scrollViewPanStateDidChange:change];
}

- (void)setShowInsetTop:(BOOL)showInsetTop {
    _showInsetTop = showInsetTop;
    
}

- (void)backInitState {
    
}

@end

四、在TableView使用Refresh

在设置UITableView 的mj_header，来进行使用下拉刷新动画效果。

- (void)configureRefresh {
    __weak typeof(self) weakSelf = self;
    INRefreshHeader *header = [INRefreshHeader headerWithRefreshingBlock:^{
        [weakSelf refreshData];
    }];
    
    self.noteView.tableView.mj_header = header;
}

- (void)refreshData {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self.noteView.tableView.mj_header endRefreshing];
    });
}

- (void)loadMoreData {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self.noteView.tableView.mj_header endRefreshing];
    });
}

Lottie实现下拉刷新动画效果如下

五、小结

iOS开发-Lottie实现下拉刷新动画效果

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