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最新评论
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zjjzmw1:
...
转载:IOS开发之——objectForKey与valueForKey在NSDictionary中的差异 -
hldfxh:
解决了我的问题
JSON Lib, XML转JSON字符串不要namespace,以及处理特殊xml属性"type" -
herry68:
可以给我提供以下你的这个NSData+Base64.h类吗
图片转base64串及反转回图片 -
herry68:
我用这个方法把图片转换成nsstring成功了,但是从nsst ...
图片转base64串及反转回图片 -
hibluse:
handy.wang 写道hibluse 写道我已经设置了WA ...
基于FMDB-SQLite的App数据库性能优化
A run loop is a mechanism that provides the possibility for the system to wake up sleeping threads to manage asynchronous events. Normally when you run a thread (with the exception of the main thread) you have the option to start for it a run loop or not. If the thread does some sort or long-runnign operation with no interaction with external events and no timers, you don't need a run loop, but if your thread needs to respond to incoming events, you need to attach it to a run loop in order to wake up this thread when new events arrive. This is the case of NSURLConnection generated threads, as the live on incoming events only (from the network).
Each thread can be associated to different run loops, or it can be associated to a run loop but this run loop can be set to work on different modes. A "run loop mode" is a convention used by the OS to establish some rules on when delivering certain events or simply suspend this delivery and then collect them all to be delivered later. Usually all run loop are set to the "default mode" which establishes a default way to manage input events. As soon as some mouse-dragging (Mac OS) or touch (on iOS) event happens then the mode for this run loop is set to event tracking: this means that the thread will not be woke up on new network events but these events will be delivered later when the user input event terminates and the run loop set to default mode again: obviously this is a choice made by the OS architects to give priority to user events instead of background events.
If you decide to change the run loop mode for your NSURLConnection thread, by using the
scheduleInRunLoop:forModes:
method, then you allow the thread's events to be associated not to a specific run loop (the default) but to a different run loop mode. In particular the special pseudo-mode called "common" allows to permanently associate the input sources to all modes that are - or will be - associated to the "common mode". Of course event tracking mode is part of this family of modes, so the method applied on NSURLConnection's instance means: please associate the connection source events to "tracking mode" in addition to "default mode".
Finally you can add new modes to the common modes, but this is a quite low-level operation.
I would to close by adding a few notes: - typically we need to associate to a table view a set of images or thumbnails downloaded from the network; even if we may thing that download these images from the network while the table view is scrolling could improve the UI (because we can see the images while scrolling) infact this is dangerous as the final effect will be a scrolling not fluid. So don't add NSURLConnection to the run loop in such case but use the UIScrollView delegate methods to detect when scrolling is terminated to update the table and download new items from the network - you may consider to use GCD which will help you to "shield" your code from run loop management issues. So in the example above, you may consider to add your network requests to a custom serial queue.
from: http://stackoverflow.com/questions/7222449/nsdefaultrunloopmode-vs-nsrunloopcommonmodes
发表评论
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图片转base64串及反转回图片
2013-07-29 12:04 2207图片转base64串: UIImage *_ori ... -
iOS中异步函数的单元测试
2013-06-08 09:51 1470转载自:http://blog.csdn.net/diyag ... -
拆数算法(ObjectiveC递归实现)
2013-03-21 10:45 1850把一个大数拆成几个指定的小数相加,以下实现方式性能很差仅供参考 ... -
[iPhone高级] 基于XMPP的IOS聊天客户端程序(IOS端一)
2012-12-16 15:56 8537转载自:http://blog.csdn.net/kangka ... -
复杂数据类型变量的引用计数与block以及__block修饰符的关系
2012-12-14 17:05 4789以下结论是结合参考资料和实验得来,不对地方请大家纠正: ... -
基于FMDB-SQLite的App数据库性能优化
2012-12-14 16:48 110791)如果数据库配置成为串行模式:sqlite3_con ... -
Run Loop
2012-08-24 11:12 1147来源:http://www.cnblogs.com/scorp ... -
转载:IOS开发之——objectForKey与valueForKey在NSDictionary中的差异
2012-08-23 15:49 1262来源:http://blog.csdn.net/pjk1 ... -
深拷贝和浅拷贝
2012-08-23 15:44 903来源:http://blog.csdn.net/pjk1129 ... -
静态全局变量的内存问题
2012-08-23 15:43 1098来源:http://blog.csdn.net/pjk1 ... -
如何将iPhone模拟器的分辨率调整至1136x640?
2012-08-09 10:01 3091来源:http://www.weiphone ... -
AtoS查看iOS Crash log中的16进制代码日志
2012-08-02 17:21 3362注意:crash_log一定要和打包时的archive对应上; ... -
Objective-c 中 nil, Nil, NULL和NSNull的区别
2012-08-02 10:40 906来自:http://blog.csdn.net/yhawaii ... -
XCODE4.3.2与真机联调时,console里输出中文乱码
2012-07-19 13:34 1275修改项目的scheme的info,把debugger由LLDB ... -
NSAutoReleasePool使用中drain和release的区别
2012-05-30 14:50 1620虽然ARC引入之后NSAutoReleasePool的使 ... -
Network Link Conditioner in Lion
2012-05-21 14:46 1822Network Link Conditioner in ... -
PushMeBaby中的神秘错误代码OSStatus的实际含义
2012-05-03 09:31 74981)查看SecureTransport.h中 / ... -
NSParameterAssert
2012-04-20 09:38 2592NSParameterAssert Valida ... -
线程内sleep
2012-04-19 09:20 1000[NSThread sleepForTim ... -
转换Xcode里打印的unicode编码日志
2012-04-18 20:33 17391)打开Terminal 2)输入python 3)pri ...
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