我有 UIWebview 可以对外部服务进行 AJAX 调用。离线时我需要捕获这些请求并返回本地 json。
我实现了一个 NSURLProtocol 并且我设法捕获了 AJAX 请求,问题是 jquery 总是返回 0 错误代码:
$.ajax({
url: url,
dataType: 'json',
contentType: "application/json",
success: function(jsonData){
alert("success :");
},
error: function (request, status, error) {
alert("failure :" + request.status );
}
});
我总是得到一个 request.status = 0
为了测试我的协议(protocol),我尝试在我的 html 中模拟一张图片,效果很好。
- 对来自 google.fr 的图像的 HTML 请求 => 工作正常
- AJAX 调用亚马逊上的 json => 失败
这是我的完整实现:
#import "EpubProtocol.h"
@implementation EpubProtocol
#pragma mark - NSURLProtocol
+ (BOOL)canInitWithRequest:(NSURLRequest *)request {
BOOL awsRequest = [self request:request contains:@"s3.amazonaws.com"];
BOOL imgRequest = [self request:request contains:@"google.fr"];
BOOL match = awsRequest || imgRequest;
return match;
}
+ (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 mimeType:@"application/json" data:data];
}
//Mock image call
else if([EpubProtocol request:request contains:@"google.fr"]) {
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.itespresso.fr/wp-content/gallery/yahoo/1-yahoo-logo.jpg"]] queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
[self mockRequest:request mimeType:@"image/jpeg" 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 mimeType:(NSString*)mimeType data:(NSData*)data {
id client = [self client];
NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:[request URL] MIMEType:mimeType expectedContentLength:-1 textEncodingName:nil];
[client URLProtocol:self didReceiveResponse:response
cacheStoragePolicy:NSURLCacheStorageNotAllowed];
[client URLProtocol:self didLoadData:data];
[client URLProtocolDidFinishLoading:self];
}
@end
最佳答案
问题来自 webkit,由于跨域源请求而阻止响应。由于我们模拟响应,因此我们必须强制访问控制允许来源。
然后我们还需要强制响应的内容类型。
神奇的地方就在这里:
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];
协议(protocol)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 中没有什么特别的:
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 );
}
});
}
关于ios - 如何使用 NSURLProtocol 模拟 AJAX 调用?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15224071/