1. A method for blocking a webpage based on an iOS device, which is applied in an iOS device comprising an application program and a system component, wherein, the method comprises following steps: S1) starting the application program, creating a subclass object of URL (Uniform Resource Locator) cache class, and pointing the subclass object as a cache object of uniform resource locator, in which the cache object of uniform resource locator is a visited object when a web request is send by the system component; S2) obtaining, by the application program, HTTP (Hypertext transfer protocol) address entered by a user, generating a first request information according to the HTTP address, and sending the first request information to the system component; S3) monitoring, by the application program, a web request sent by the system component via the subclass object; S4) obtaining, by the application program, a second request information from the system component, and parsing the second request information so as to obtain a uniform resource locator character string included in the second request information, when the web request is successfully monitored by the application program; S5) matching, by the application program, a link character string with the parsed uniform resource locator character string, if the match is success, executing Step S6; while if the match fails, executing Step S7; S6) generating, by the application program, a fake-response data, returning the fake-response data to the system component, displaying the fake-response data via the system component, and returning to Step S3; and S7) sending, by the application program, the second request information to a web server, receiving response information returned from the web server, sending the response information to the system component, and returning to Step S3.