如何使用NSURLProtocol模拟AJAX调用？

问题来自webkit，由于跨域起源请求而阻止了响应。由于我们模拟了响应，因此我们必须强制执行A​​ccess-Control-Allow-Origin。

然后，我们还需要强制响应的内容类型。

这是魔术发生的地方：

NSDictionary *headers = @{@"Access-Control-Allow-Origin" : @"*", @"Access-Control-Allow-Headers" : @"Content-Type"};NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:request.URL statusCode:200 HTTPVersion:@"1.1" headerFields:headers];

该协议的最终实现：

#import "EpubProtocol.h"@implementation EpubProtocol#pragma mark - NSURLProtocol+ (BOOL)canInitWithRequest:(NSURLRequest *)request {    BOOL isAwsRequest = [self request:request contains:@"s3.amazonaws.com"];    return isAwsRequest;}+ (NSURLRequest*)canonicalRequestForRequest:(NSURLRequest*)theRequest{    return theRequest;}- (void)startLoading {    NSURLRequest *request = [self request];    //Mock Amazon call    if([EpubProtocol request:request contains:@"s3.amazonaws.com"]) {        NSString *path = [[NSBundle bundleForClass:self.class] pathForResource:@"epub1" ofType:@"json"];        NSData *data = [NSData dataWithContentsOfFile:path];        [self mockRequest:request data:data];    }}- (void)stopLoading{    NSLog(@"Did stop loading");}#pragma mark - Request utils+ (BOOL) request:(NSURLRequest*)request contains:(NSString*)domain {    NSString *str = [[request URL] absoluteString];    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF contains[cd] %@", domain];    return [pred evaluateWithObject:str];}#pragma mark - Mock responses-(void) mockRequest:(NSURLRequest*)request data:(NSData*)data {    id client = [self client];    NSDictionary *headers = @{@"Access-Control-Allow-Origin" : @"*", @"Access-Control-Allow-Headers" : @"Content-Type"};    NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:request.URL statusCode:200 HTTPVersion:@"1.1" headerFields:headers];    [client URLProtocol:self didReceiveResponse:response     cacheStoragePolicy:NSURLCacheStorageNotAllowed];    [client URLProtocol:self didLoaddata:data];    [client URLProtocolDidFinishLoading:self];}@end

JS没什么特别的：

function loadJSonDoc(){  var url = "https://s3.amazonaws.com/youboox_recette/epub.json";  $.ajax({      url: url,      dataType: 'json',       contentType: "application/json",      success: function(jsonData){        alert('success');        document.getElementById("myDiv").innerHTML='<p>'+$.param(jsonData)+'</p>';      },      error: function (request, status, error) {        alert("failure :" + request.status );      }  });}