iOS实现逐帧动画做loading视图

本文实例为大家分享了iOS实现逐帧动画做loading视图的具体代码，供大家参考，具体内容如下

我封装了一个可复用的loading视图组件，用于按照一定周期逐帧播放加载动画。代码如下：

.h文件

#import <UIKit/UIKit.h>

//加载状态
typedef enum {
    FZImageSequenceLoadingStatusStop = 1,          // 停止
    FZImageSequenceLoadingStatusLoading,         // 加载中
    FZImageSequenceLoadingStatusError   //发生错误
} FZImageSequenceLoadingStatus;

@interface FZImageSequenceLoadingView : UIView {
    UIImageView *_imageView;
    UILabel *_lblMsg;
    NSTimer *timer;
    int currentImageIndex;
}

@property(strong) NSArray *imageArray;  //动画序列的图片数组

@property(strong, nonatomic) UIImage *errorImage;

@property(nonatomic, strong) NSString *errorMsg;

@property(nonatomic, strong) NSString *loadingMsg; //提示文字

@property(nonatomic) CGRect imageFrame; //图片的Frame

@property(nonatomic) CGRect msgFrame;   //文字内容的Frame

@property(nonatomic) float timerInterval; //切换图片的周期

/**
 切换状态
 */
- (void)switchToStatus:(FZImageSequenceLoadingStatus)status;

/**
 通过图片名字和数量设置图片数组，如给定名字"name"、“.png”和数量4，则会去加载“name_1.png”到"name_4.png"的图片
 */
- (void)setImageArrayByName:(NSString *)name andExtName:(NSString *)extName andCount:(int)count;

@end

.m文件

#import "FZImageSequenceLoadingView.h"

@implementation FZImageSequenceLoadingView

@synthesize errorImage;
@synthesize errorMsg;
@synthesize imageArray;
@synthesize loadingMsg;
@synthesize timerInterval;

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        timerInterval = 1;
        currentImageIndex = -1;
    }
    return self;
}

/*
 // Only override drawRect: if you perform custom drawing.
 // An empty implementation adversely affects performance during animation.
 - (void)drawRect:(CGRect)rect
 {
 // Drawing code
 }
 */

- (void)setupSubviews {
//    self.backgroundColor = [UIColor redColor];
    if (self.imageArray && self.imageArray.count > 0) {
        if (!_imageView) {
            _imageView = [[UIImageView alloc] init];
            [self addSubview:_imageView];
        }
        //让图片view为本view的顶部居中，大小为图片数组中的第一张
        UIImage *firstImg = [self.imageArray objectAtIndex:0];
        _imageView.size = firstImg.size;
        _imageView.top = 0;
        _imageView.left = (self.size.width - _imageView.size.width) / 2;
    }

    if (self.loadingMsg) {
        CGSize labelSize = [self.loadingMsg sizeWithFont:[UIFont systemFontOfSize:11]];
        if (!_lblMsg) {
            _lblMsg = [[UILabel alloc] initWithFrame:CGRectZero];
            _lblMsg.textAlignment = NSTextAlignmentCenter;
            [self addSubview:_lblMsg];
        }
        _lblMsg.font = [UIFont systemFontOfSize:11];
        _lblMsg.size = labelSize;
        _lblMsg.textColor = [UIColor darkGrayColor];
        _lblMsg.backgroundColor = [UIColor clearColor];
        _lblMsg.bottom = self.height;
        _lblMsg.left = (self.width - _lblMsg.width) / 2;
    }
}

- (void)switchToStatus:(FZImageSequenceLoadingStatus)status {
    if (!_lblMsg || !_imageView) {
        [self setupSubviews];
    }
    switch (status) {
        case FZImageSequenceLoadingStatusError:
            [self switchToError];
            break;
        case FZImageSequenceLoadingStatusLoading:
            [self switchToLoading];
            break;
        case FZImageSequenceLoadingStatusStop:
            [self switchToStop];
            break;
    }
}

- (void)switchToStop {
    [timer invalidate];
    timer = nil;
    if (self.imageArray && self.imageArray.count > 0) {
        _imageView.image = [self.imageArray objectAtIndex:0];
    }
}

- (void)switchToError {
    [timer invalidate];
    timer = nil;
    //如果有错误状态的图
    if (self.errorImage) {
        _imageView.image = self.errorImage;
        //如果没有就用第一张动画图
    } else if (self.imageArray && self.imageArray.count > 0) {
        _imageView.image = [self.imageArray objectAtIndex:0];
    }

    if (self.errorMsg) {
        _lblMsg.text = self.errorMsg;
    }
}

- (void)switchToLoading {
    if (self.loadingMsg) {
        _lblMsg.text = self.loadingMsg;
    }
    if (!timer) {
        timer = [NSTimer scheduledTimerWithTimeInterval:self.timerInterval target:self selector:@selector(showNextImage) userInfo:nil repeats:YES];
    }
}

- (void)showNextImage {
    if (!imageArray || imageArray.count < 1) {
        return;
    }
    currentImageIndex = (currentImageIndex + 1) % self.imageArray.count;
    // 主线程执行：
    dispatch_async(dispatch_get_main_queue(), ^{
        _imageView.image = [imageArray objectAtIndex:currentImageIndex];
    });
}

- (void)setImageArrayByName:(NSString *)name andExtName:(NSString *)extName andCount:(int)count {
    NSAssert((name && extName && (count > 0)), @"图片名字和数量错误");
    NSMutableArray *imgs = [NSMutableArray arrayWithCapacity:count];
    for (int i = 1; i <= count; i++) {
        NSString *imgName = [NSString stringWithFormat:@"%@_%i%@", name, i, extName];
        UIImage *image = [UIImage imageNamed:imgName];
        NSLog(@"%@", image);
        if (!image) {
            continue;
        }
        [imgs addObject:image];
    }
    self.imageArray = imgs;
}

@end

使用示例，在uiwebview中使用如下：

初始化视图：

//设置loading视图
- (void)setupLoadingView {
    if (!_loadingView) {
        _loadingView = [[FZImageSequenceLoadingView alloc] initWithFrame:CGRectMake(0, 0, 170, 70)];
        _loadingView.center = self.view.center;
        [_loadingView setImageArrayByName:@"loading" andExtName:@".png" andCount:10];
        _loadingView.loadingMsg = @"努力加载中，请稍候";
        _loadingView.errorMsg = @"加载失败";
        _loadingView.timerInterval = 0.1;
        _loadingView.hidden = YES;
        [self.view addSubview:_loadingView];
    }
}

在uiwebview的代理方法中切换状态：

#pragma mark - webview delegate
- (void)webViewDidStartLoad:(UIWebView *)webView {
    if (_loadingView.hidden) {
        _loadingView.hidden = NO;
        [_loadingView switchToStatus:FZImageSequenceLoadingStatusLoading];
    }
}

- (void)webViewDidFinishLoad:(UIWebView *)webView {
    if (!_loadingView.hidden) {
        [_loadingView switchToStatus:FZImageSequenceLoadingStatusStop];
        _loadingView.hidden = YES;
    }

}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
    NSLog(@"load page error:%@", [error description]);
    if (!_loadingView.hidden) {
        [_loadingView switchToStatus:FZImageSequenceLoadingStatusError];
    }
}

目前该组件功能还不够完善，但是能满足目前我自己的需求，后续再继续丰富。

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