在iOS项目中使用WebP

SDWebImage中支持WebP格式的，可以完成UIImage -> Webp和WebP -> UIImage的转换。直接通过CocoaPods的Podfile文件中加入pod 'SDWebImage/WebP'即可。

可能会遇到libwebp v0.6.0 超时问题:iOS使用cocoapods 安装 libwebp0.6.0 遇到Error installing libwebp

SDWebImage/WebP提供了UIImage+WebP的Category里面有个将WebP NSData的数据转换为UIImage的方法：

+ (UIImage *)sd_imageWithWebPData:(NSData *)data;

1. 在Native中使用WebP格式图片

NSString *path = [[NSBundle mainBundle] pathForResource:@"logo" ofType:@"webp"];
NSData *data = [[NSData alloc] initWithContentsOfFile:path];
UIImage *img = [UIImage sd_imageWithWebPData:data];
self.imageView.image = img;

2. 在UIWebView中使用WebP格式图片

具体实现是通过NSURLProtocol拦截WebView的网络请求，筛选出请求Webp图片的网络请求，下载完Webp图片后使用谷歌的WebP解析库解析图片，转换成Jpg格式图片,传给网页。

.h

#import <Foundation/Foundation.h>

@interface TTWebPURLProtocol : NSURLProtocol

@end

.m

#import "TTWebPURLProtocol.h"
#import "UIImage+MultiFormat.h"

static NSString *const TTWebPProtocolHandledKey = @"TTWebPProtocolHandledKey";

@interface TTWebPURLProtocol ()<NSURLSessionTaskDelegate, NSURLSessionDataDelegate>

@property (nonatomic, strong) NSURLSession *session;
@property (nonatomic, strong) NSURLSessionDataTask *sessionTask;

@property (nonatomic, strong) NSMutableData *imgData;

@end

@implementation TTWebPURLProtocol

+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
    if ([NSURLProtocol propertyForKey:TTWebPProtocolHandledKey inRequest:request]) {
        return NO;
    }
    
    NSURL *url = [request URL];
    NSString *userAgent = [request allHTTPHeaderFields][@"User-Agent"];
    if (![[userAgent lowercaseString] containsString:@"applewebkit"]) {
        return  NO;
    }
    
    NSString* const requestFiletype = [[url pathExtension] lowercaseString];
    NSLog(@"---------------%@",url);
    return [@"webp" isEqualToString:requestFiletype];
}

+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request
{
    return request;
}

- (void)startLoading
{
    NSMutableURLRequest *mutableReqeust = [[self request] mutableCopy];
    [NSURLProtocol setProperty:@YES forKey:TTWebPProtocolHandledKey inRequest:mutableReqeust];

    self.sessionTask = [self.session dataTaskWithRequest:self.request];
    [self.sessionTask resume];
}

- (void)stopLoading
{
    [self.sessionTask cancel];
    self.sessionTask = nil;
}


#pragma mark -- NSURLSessionTaskDelegate
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didReceiveResponse:(NSURLResponse *)response
 completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler
{
    self.imgData = [[NSMutableData alloc] init];
    [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
    
    if (completionHandler) {
        completionHandler(NSURLSessionResponseAllow);
    }
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
    didReceiveData:(NSData *)data
{
    [self.imgData appendData:data];
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
    didCompleteWithError:(nullable NSError *)error
{
    if (error) {
        [self.client URLProtocol:self didFailWithError:error];
        return;
    }
    
    UIImage *webpImg = [UIImage sd_imageWithData:self.imgData];
    NSData *imgData  = UIImageJPEGRepresentation(webpImg, 1);
    
    [self.client URLProtocol:self didLoadData:imgData];
    [self.client URLProtocolDidFinishLoading:self];

}

#pragma mark -- Setter && Getter
- (NSURLSession *)session
{
    if (!_session) {
        
        NSURLSessionConfiguration *sessonConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
        _session = [NSURLSession sessionWithConfiguration:sessonConfig delegate:self delegateQueue:nil];
    }
    return _session;
}

最后:
使用TTWebPURLProtocol前需要注册，推荐在APPDelegate中的- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(nullable NSDictionary *)launchOptions;的方法中加入如下代码：

[NSURLProtocol registerClass:[TTWebPURLProtocol class]];

提示: 图片链接必须是以.webp结尾.

代码摘自: https://www.jianshu.com/p/adc1f4c89287