//清除cookies
NSHTTPCookie *cookie;
NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
for (cookie in [storage cookies]){
[storage deleteCookie:cookie];
}
//清除UIWebView的缓存
[[NSURLCache sharedURLCache] removeAllCachedResponses];
NSURLCache * cache = [NSURLCache sharedURLCache];
[cache removeAllCachedResponses];
[cache setDiskCapacity:0];
[cache setMemoryCapacity:0];
NSString *libraryPath = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *cookiesFolderPath = [libraryPath stringByAppendingString:@"/Cookies"];
NSError *errors;
[[NSFileManager defaultManager] removeItemAtPath:cookiesFolderPath error:&errors];