如何使用Foxit PDF SDK for iOS加密PDF文件

Foxit PDF SDK提供了一系列加密和解密功能，以满足不同级别的文档安全保护。用户可以使用常规密码加密和证书驱动加密，或使用自己的安全处理机制来自定义安全实现。

如何使用密码加密PDF文件

#import "ViewController.h"
#import <FoxitRDK/FSPDFViewControl.h>
...

// Encrypt the source pdf document with specified owner password and user password, the encrypted PDF will be saved to the path specified by parameter savePath.
- (BOOL) encryptPDF:(FSPDFDoc*) pdfDoc ownerPassword:(NSString*)ownerPassword userPassword:(NSString*)userPassword savedPath:(NSString*)savedPath
{
    if(!pdfDoc || (!ownerPassword && !userPassword) || !savedPath)
        return NO;
    // The encryption setting data. Whether to encrypt meta data:YES, User permission: modify,assemble,fill form. Cipher algorithm:AES 128.
    FSStdEncryptData* encryptData = [[FSStdEncryptData alloc] initWithIs_encrypt_metadata:YES user_permissions🙁FSPDFDocPermModify| FSPDFDocPermAssemble|FSPDFDocPermFillForm) cipher:FSSecurityHandlerCipherAES key_length:16];
    FSStdSecurityHandler * stdSecurity = [[FSStdSecurityHandler alloc] init];
    if(![stdSecurity initialize:encryptData user_password:userPassword owner_password:ownerPassword])
        return NO;
    [pdfDoc setSecurityHandler:stdSecurity];
    if(![pdfDoc saveAs:savedPath save_flags:FSPDFDocSaveFlagNormal])
        return NO;
    return YES;
}