iOS在所有请求里添加Header

服务器要求在所有请求当中添加Header进行验证，

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType方法拦截不到相关的css,js文件请求。这里要用NSURLProtocol，这是一个挺牛逼的类，它是一个抽象类,不能去实例化它,只能子类化NSURLProtocol，每次在对一个 URL 进行请求的时候 URL Loading System 都会向 已经注册的 Protocol 询问是否可以处理该请求。这里就看出他的作用来了. 比如: 拦截UIWebView的请求,忽略请求,重定向... ...

直接贴代码：

#import <Foundation/Foundation.h>

@interface NSURLProtocolCustom : NSURLProtocol
@end

#import "NSURLProtocolCustom.h"
static NSString* const FilteredKey = @"FilteredKey";
@interface NSURLProtocolCustom ()<NSURLSessionDataDelegate>
@property (atomic, strong, readwrite) NSURLSessionDataTask *task;
@property (nonatomic, strong        ) NSURLSession         *session;
@end

@implementation NSURLProtocolCustom
+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
    //只处理http和https请求
    NSString *scheme = [[request URL] scheme];
    if ( ([scheme caseInsensitiveCompare:@"http"] == NSOrderedSame ||
          [scheme caseInsensitiveCompare:@"https"] == NSOrderedSame))
    {
        //看看是否已经处理过了，防止无限循环
        if ([NSURLProtocol propertyForKey:FilteredKey inRequest:request]) {
            return NO;
        }
        return YES;
    }
    return NO;
}

+ (NSURLRequest *) canonicalRequestForRequest:(NSURLRequest *)request {
    /** 可以在此处添加头等信息  */
    NSMutableURLRequest *mutableReqeust = [request mutableCopy];
    [mutableReqeust setValue:@"abc" forHTTPHeaderField:@"Authorization"];
    return mutableReqeust;
}
- (void)startLoading
{
    NSMutableURLRequest *mutableReqeust = [[self request] mutableCopy];
    //打标签，防止无限循环
    [NSURLProtocol setProperty:@YES forKey:FilteredKey inRequest:mutableReqeust];
    
    NSURLSessionConfiguration *configure = [NSURLSessionConfiguration defaultSessionConfiguration];
    
      NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    
    self.session  = [NSURLSession sessionWithConfiguration:configure delegate:self delegateQueue:queue];
    self.task = [self.session dataTaskWithRequest:mutableReqeust];
    [self.task resume];
}

- (void)stopLoading
{
    [self.session invalidateAndCancel];
    self.session = nil;
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
    if (error != nil) {
        [self.client URLProtocol:self didFailWithError:error];
    }else
    {
        [self.client URLProtocolDidFinishLoading:self];
    }
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didReceiveResponse:(NSURLResponse *)response
 completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler
{
    [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
    
    completionHandler(NSURLSessionResponseAllow);
}

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

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask willCacheResponse:(NSCachedURLResponse *)proposedResponse completionHandler:(void (^)(NSCachedURLResponse * _Nullable))completionHandler
{
    completionHandler(proposedResponse);
}

//TODO: 重定向
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task willPerformHTTPRedirection:(NSHTTPURLResponse *)response newRequest:(NSURLRequest *)newRequest completionHandler:(void (^)(NSURLRequest *))completionHandler
{
    NSMutableURLRequest *    redirectRequest;
    redirectRequest = [newRequest mutableCopy];
    [[self class] removePropertyForKey:FilteredKey inRequest:redirectRequest];
    [[self client] URLProtocol:self wasRedirectedToRequest:redirectRequest redirectResponse:response];
    
    [self.task cancel];
    [[self client] URLProtocol:self didFailWithError:[NSError errorWithDomain:NSCocoaErrorDomain code:NSUserCancelledError userInfo:nil]];
}

- (instancetype)initWithRequest:(NSURLRequest *)request cachedResponse:(NSCachedURLResponse *)cachedResponse client:(id<NSURLProtocolClient>)client
{
    self = [super initWithRequest:request cachedResponse:cachedResponse client:client];
    if (self) {
        
        // Some stuff
    }
    return self;
}

@end

最后在用到的webview类里进行注册和注销即可

- (void)viewDidLoad {
    [super viewDidLoad];
    [NSURLProtocol registerClass:[NSURLProtocolCustom class]];
}

-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    [NSURLProtocol unregisterClass:[NSURLProtocolCustom class]];
}