App Store上的应用都使用了DRM(Digital Rights Management)数字版权加密保护技术，想更多了解DMG历史请戳这里。首先得破解加密的可执行文件，可以通过编译dumpdecrypted来解密，原理是让app预先加载一个解密的dumpdecrypted.dylib，然后在程序运行后，将代码动态解密，最后在内存中dump出来整个程序。（如果没有越狱设备，可以通过第三方市场下载未加密的ipa文件，跳过此步骤）。
Class cls = NSClassFromString(@"LSApplicationWorkspace"); id s = [(id)cls performSelector:NSSelectorFromString(@"defaultWorkspace")]; NSArray *arr = [s performSelector:NSSelectorFromString(@"allInstalledApplications")]; Class Proxy = NSClassFromString(@"LSApplicationProxy");
for (id proxy in arr) { id bundleID = [proxy valueForKey:@"applicationIdentifier"]; if (bundleID && [bundleID isEqualToString:@"net.oschina.iosapp"]) { id dataUrl = [proxy valueForKey:@"dataContainerURL"]; NSLog(@"dataUrl : %@",dataUrl); } }
如果显示dumpdecrypted.dylib: stat() failed with errno=1 即“Operation not permitted”，表示操作权限不够，可以将dumpdecrypted.dylib文件sip至手机的usr/lib目录下，然后再执行DYLD_INSERT_LIBRARIES=dumpdecrypted.dylib命令编译，此时会在usr/lib目录下生成iosapp.decrypted文件。
- (void)didReceiveRemoteNotification:(NSDictionary *)remoteNotification withCompletion:(void (^)(WKUserNotificationInterfaceType))completionHandler { // This method is called when a remote notification needs to be presented. // Implement it if you use a dynamic notification interface. // Populate your dynamic notification interface as quickly as possible. // // After populating your dynamic notification interface call the completion block. completionHandler(WKUserNotificationInterfaceTypeCustom); }
不同与UIKit，很多视图控件无法通过手写的方式来管理，需要在Interface.storyboard中设置参数。比如WKInterfaceLabel需要多行显示和滚动时，需要设置Label->Lines为0，Size->Width为Relative to Container，以及Size->Height为Size To Fit Content，意为宽度与父视图一样，高度为内容自适应，即可实现多行显示与滚动了。
Watch OS 2引入了ClockKit与WatchConnectivity框架，不仅增强了表盘自定义控件的灵活性，数据共享操作改进很大，其中extension 是直接存在于手表中的，在Watch OS 1中通过app group管理的方式已经失效。另外HealthKit也得到增强，健康监护及运动统计类的App会大有施展空间。
OpenSSH_6.9p1, LibreSSL 2.1.8 debug1: Reading configuration data /Users/pandora/.ssh/config debug1: /Users/pandora/.ssh/config line 2: Applying options for github.com debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 21: Applying options for * debug1: Connecting to github.com [192.30.252.129] port 22. debug1: Connection established. debug1: identity file /Users/pandora/.ssh/id_rsa_dama2716588 type1 debug1: key_load_public: No such file or directory debug1: identity file /Users/pandora/.ssh/id_rsa_dama2716588-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.9 debug1: Remote protocol version 2.0, remote software version libssh-0.7.0 debug1: no match: libssh-0.7.0 debug1: Authenticating to github.com:22 as 'git' debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client chacha20-poly1305@openssh.com <implicit> none debug1: kex: client->server chacha20-poly1305@openssh.com <implicit> none debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ssh-rsa SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8 debug1: Host 'github.com' is known and matches the RSA host key. debug1: Found key in /Users/pandora/.ssh/known_hosts:1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /Users/pandora/.ssh/id_rsa_dama2716588 debug1: Server accepts key: pkalg ssh-rsa blen 279 debug1: Authentication succeeded (publickey). Authenticated to github.com ([192.30.252.129]:22). debug1: channel 0: new [client-session] debug1: Entering interactive session. debug1: Sending environment. debug1: Sending env LC_CTYPE = UTF-8 debug1: client_input_channel_req: channel 0 rtype exit-status reply 0 Hi dama2716588! You've successfully authenticated, but GitHub does not provide shell access. debug1: channel 0: free: client-session, nchannels 1 Transferred: sent 3244, received 1776 bytes, in 2.0 seconds Bytes per second: sent 1650.3, received 903.5 debug1: Exit status 1
- (void)applicationDidEnterBackground:(UIApplication *)application { bgTask = [application beginBackgroundTaskWithName:@"MyTask" expirationHandler:^{ // Clean up any unfinished task business by marking where you // stopped or ending the task outright. [application endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; }];
// Start the long-running task and return immediately. }
有些基于位置的app需要后台定时更新用户的当前位置，导致未知崩溃。原因就是Location update类型的后台任务在更新位置时，需要重新绘制MKMapView，调用了OpenGL ES，而OpenGL ES必须在程序Inactive以前关闭，不然会crash。如官方文档描述：To summarize, your app needs to call the glFinish function to ensure that all previously submitted commands are drained from the command buffer and are executed by OpenGL ES. After it moves into the background, you must avoid all use of OpenGL ES until it moves back into the foreground.
Class extension常常被误解为一个匿名的category。它们的语法的确很相似。虽然都可以用来为一个现有的类添加方法和属性，但它们的目的和行为却是不同的，category和extensions的不同在于后者可以添加属性；另外类扩展添加的方法是必须要实现的；可以运行时给category通过objc_setAssociatedObject、objc_getAssociatedObject添加和读取属性。
