we all know，There is pyenv when using Python，If you use ruby, there is rbenv，Can easily control and manage the version of the programming language environment，Then，Is there any way，Can Xcode switch versions like this?
Every time Xcode releases an update，More or not has become a problem，Difficult to download，Can't resume，Can't use third-party tools to download，It's really terrible... not to mention the compatibility issue when multiple versions。
use xcode-install，One time[……]
Normal，You will encounter this error when installing a Python package，This package must be a package containing C ++ code。
This is due to incompatibility after macOS update，In General，The maintainer of this package should already be compatible with this particular situation：
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1 2 |
if platform.system() == 'Darwin': extra_compile_args += ['-mmacosx-version-min=10.7', '-stdlib=libc++'] |
So that it can be successfully compiled on macOS。
But if you are using PyPy，Maybe even if the maintainer includes this sentence，You can't succeed[……]
Recently doing text statistics，Implemented in Python，Encountered an interesting problem-how to save statistical results。
Writing directly into memory is really impossible，Memory exhausted after ten hours，The program was forced to close。If you write directly to the database，Each write is too slow，It's been more than ten hours，If you go on like this, you will have to count on the week，Not a solution。
At last，I thought of a solution that combines both-using memory as a buffer，After reaching a certain amount, all the current data will be merged into the hard disk at one time。
But then there is a threshold，How to confirm[……]
In Safari 9 before，We just download a safariextz file and double click on it，So that Safari can load this plugin。The benefit is definitely very convenient，But it ’s also not very secure (plugins that can be downloaded everywhere，It is likely to have been tampered with)。
So later，Apple no longer allows users to directly download plug-ins to install on Safari，App must be downloaded from Mac Apple Store，Then the Safari plugin is provided in the form of a plugin in the app，With App[……]
Before I wrote an article，Use fail2ban Bind9 be used to prevent DNS amplification attacks，Never imagined，original Wordpress It can also be used for amplification attacks，The principle is its Pingback mechanism。
Pingback is a tool for notifying each other of a Wordpress website，For example, A blog refers to a link to a B blog post，Then Wordpress can automatically help you inform B blog，Tell the blogger that you quoted his article。
This[……]
When developing iOS apps，Many applications need to set the color of the iOS system status bar according to the current App content color，Black or white-especially on iOS 13 After the system supports the black mode。
Normal，Others will tell you to do this：
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1 |
UIApplication.shared.statusBarStyle = .default |
But this triggers a warning： Deprecated in iOS 9 。So is there any other way? Have，The official recommendation is[……]
Before I wrote an article：《 Use Mailgun create your free domain mail 》Mailgun There is a very interesting feature is the recipient routing，With this feature set，You can use any incoming mail forwarding to your mailbox which set a good，This eliminates the need for each domain name to set up a mail service，Only through Mailgun On the corresponding e-mail can be forwarded by e-mail needs - after all,，Usually we will use these domain mail may be a basic authentication。
Recently，Mailgun no longer free，Free users[……]
It has been a very popular self-signed certificate for HTTPS decryption，Then there are a lot of people realize crack of App by modifying Apple's internal purchase receipt。In fact Verified Purchase should be connected to the server App，Server to communicate with Apple's servers，The results are then sent to the App - but a lot of developers (including individual developers and corporate developers) do not bother to go to a special server maintenance，So communicate directly with the App and Apple's servers，This provides an opportunity for middle attacks。
Middle attack，It means when A and B communicate[……]
Many people will encounter in the development EXC_BAD_ACCESS ，I'm sorry，This time, Xcode does not give any detailed solutions。
In general，This is due to a memory error caused。In simple terms it is that you create an object A，But in the later time of the visit，A memory in this area have been moved to do the system he used，Put objects such as B here - A your left hand，The actual content does not exist。
Then there will be such a collapse similar：
[crayon-672[……]