这篇文章给大家分享的是有关iOS如何实现逐帧动画做loading视图的内容。小编觉得挺实用的，因此分享给大家做个参考，一起跟随小编过来看看吧。
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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