问题：
ajax跨域访问是一个老问题了，解决方法很多，比较常用的是JSONP方法，JSONP方法是一种非官方方法，而且这种方法只支持GET方式，不如POST方式安全。
即使使用jquery的jsonp方法，type设为POST，也会自动变为GET。
如果跨域使用POST方式，可以使用创建一个隐藏的iframe来实现，与ajax上传图片原理一样，但这样会比较麻烦。
因此，通过设置Access-Control-Allow-Origin来实现跨域访问
//
// JWURLProtocol.h
// NSURLProtocolExample
//
// Created by yangjw on 16/8/19.
// Copyright © 2016年 lujb. All rights reserved.
//
#import <Foundation/Foundation.h>
@interface JWURLProtocol : NSURLProtocol
@end
//
// JWURLProtocol.m
// NSURLProtocolExample
//
// Created by yangjw on 16/8/19.
// Copyright © 2016年 lujb. All rights reserved.
//
#import "JWURLProtocol.h"
static NSString * const JWURLProtocolHandledKey = @"JWURLProtocolHandledKey";
@implementation JWURLProtocol
+ (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:JWURLProtocolHandledKey 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 = [self redirectHostInRequset:mutableReqeust];
// return mutableReqeust;
return request;
}
+ (BOOL)requestIsCacheEquivalent:(NSURLRequest *)a toRequest:(NSURLRequest *)b
{
return [super requestIsCacheEquivalent:a toRequest:b];
}
- (void)startLoading
{
NSMutableURLRequest *mutableReqeust = [[self request] mutableCopy];
//打标签，防止无限循环
[NSURLProtocol setProperty:@YES forKey:JWURLProtocolHandledKey inRequest:mutableReqeust];
//异步
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:mutableReqeust queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
[self mockRequest:mutableReqeust data:data];
}];
// 同步
// NSHTTPURLResponse* urlResponse = nil;
// NSError *error = [[NSError alloc] init];
// NSData *data =[NSURLConnection sendSynchronousRequest:mutableRequest returningResponse:&urlResponse error:&error];
// [self mockRequest:mutableRequest data:data];
}
#pragma mark - Mock responses
-(void) mockRequest:(NSURLRequest*)request data:(NSData*)data {
id client = [self client];
// 问题来自于webkit块因为起源于跨域请求的响应。因为我们我们必须迫使Access-Control-Allow-Origin模拟响应，然后我们还需要强迫响应的内容类型。
// 设置为*则所域可以用ajax跨域获取数据，设置为指定的域名只能指定的域名用ajax跨域获取到数据。
NSDictionary *headers = @{@"Access-Control-Allow-Origin" : @"*", @"Access-Control-Allow-Headers" : @"Content-Type"};
NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:request.URL statusCode:200 HTTPVersion:@"1.0" headerFields:headers];
[client URLProtocol:self didReceiveResponse:response
cacheStoragePolicy:NSURLCacheStorageNotAllowed];
[client URLProtocol:self didLoadData:data];
[client URLProtocolDidFinishLoading:self];
}
- (void)stopLoading
{
}
@end
局部使用
- (void)viewDidLoad
{
[super viewDidLoad];
/** 注册 网络请求拦截 */
[NSURLProtocol registerClass:[JWURLProtocol class]];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
/** 取消注册网路请求拦截 */
[NSURLProtocol unregisterClass:[JWURLProtocol class]];
}
全局使用
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
//注册protocol
[NSURLProtocol registerClass:[JWURLProtocol class]];
return YES;
}
** 在UIWebView中使用会出现 js、css、图片重定向后无法访问的问题，如果想解决此问题可以使用此方法解决
//TODO: 重定向
- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(NSURLResponse *)response
{
if (response != nil)
{
[[self client] URLProtocol:self wasRedirectedToRequest:request redirectResponse:response];
}
return request;
}
苹果现在提倡使用NSURLSession
下面给一个完整的NSURLSession的封装类
#import <Foundation/Foundation.h>
@interface JWURLSessionProtocol : NSURLProtocol
@end
//
// JWURLSessionProtocol.m
// NSURLProtocolExample
//
// Created by yangjw on 16/8/22.
// Copyright © 2016年 lujb. All rights reserved.
//
#import "JWURLSessionProtocol.h"
static NSString * const JWURLProtocolHandledKey = @"JWURLProtocolHandledKey";
@interface JWURLSessionProtocol ()<NSURLSessionDataDelegate>
@property (atomic, strong, readwrite) NSURLSessionDataTask *task;
@property (nonatomic, strong ) NSURLSession *session;
@end
@implementation JWURLSessionProtocol
+ (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))
{
// NSLog(@"====>%@",request.URL);
//看看是否已经处理过了，防止无限循环
if ([NSURLProtocol propertyForKey:JWURLProtocolHandledKey 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];
return mutableReqeust;
}
- (void)startLoading
{
NSMutableURLRequest *mutableReqeust = [[self request] mutableCopy];
//打标签，防止无限循环
[NSURLProtocol setProperty:@YES forKey:JWURLProtocolHandledKey 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:JWURLProtocolHandledKey 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
