mrc viewability

Object-C Development tutorial -- MRC and ARC hybrid editing, object-c -- mrc After iOS5.0, you can use ARC (Automatic Reference Counting: Automatic Reference count) to replace the previous MRC (Manual Reference Counting: Manual Reference count ). Using ARC reduces the trouble of code and forgetting to release objects. But everything has two sides. If you want to

The MRC seems to have been a topic of antiquity, but I'm going to turn it around in the mood. Because, today I was asked by a question: what is the performance of Arc and MRC? Indeed, there has been no comparison before.Let's do a test first. First we need a timing helper function, I choose to use Mach_absolute_time, the function of calculating the time difference is as follows:Doublesubtracttimes (uint64_t

;}-(ID) Mutablecopywithzone: (Nszone *) zone{return_instance;}@end2:mrc#import "XMGTool.h"/** * MRC next Single implementation: 1: Need to rewrite the release method, do nothing, because do not need to release operation 2:retain will produce a new object operation will make the reference count plus 1, this time return a created instance, 3: Override the Retaincount method, Returns a maximum value*/@implemen

[IOS] single case of ARC-MRC and its application, iosmrcarc Singleton is widely used,In Singleton mode, a class has only one instance.. * It is easy for external access. * It is convenient to control the number of instances and save system resources. * Common examples in OC: UIApplication, nsnotifcenter center, NSUserDefaults, and NSFIleManager. * Single example used in the application, such as background music and sound effect management. 1. single

ARC and MRC in the iOS-ten "faces" ambush-interview magic booksI have been in touch with iOS for some time. From the first time I was a newbie who could only write NSLog, to a simple page layout that could use the basic control layout, I learned how to write core animations, every step is very pleased. I encountered various problems and various inexplicable "crashes" on the way. Fortunately, I was never frustrated. On the contrary, I was very active i

you do not consider copy MRC, the above three steps can be! If you want to support copy, you need to: (1) comply with the Nscopying Protocol (2) in the Copywithzone method, return directly to _instanceTips* General wording (lazy, a hungry man, locking): if (!_instance) _instance=[[xnsharetoolalloc]init];return_instance;* lazy type isThread not secure. So it's not written in practice. There are a hungry man, locking and so on.* But OC has its own word

objects, equivalent to retain in MRCWeak: For OC objects, equivalent to assign in MRCAssign: For basic data types, like the Assign in MRC How the object is memory-managed in Arc1.ARC under single object memory management1) under ARC, all pointers are strong pointers2) ARC, a object that wants to have a B object, then a strong pointer is needed to point to the B object3) A object does not have a B object, nothing to do, the compiler will automat

object defined by a macroThe macro definition is as follows: 12 #defineRELEASE_SAFELY(__POINTER){\[(__POINTER)release];(__POINTER)=nil;} When you perform an arc conversion check operation, Xcode will use this macro to error:Delete the macro and the place where you used the macro.The code that is commented out by the macro is not processed by Xcode at the time of conversion.PS: This is quite a bit of a pit, because you simply can't anticipate how many macros are b

1. ARC MRC Hybrid DevelopmentWhat happens to third-party libraries that are developed using MRC in project development?For example: ASI1> Attempt to use Xcode's conversion tool (high failure rate)2> in the Compile option, add the-FNO-OBJC-ARC tag for the MRC program, indicating that at compile time, the file uses MRC

Tags: MRC and arcAfter os5.0, you can use arc (automatic reference counting: automatic reference count) to replace the previous MRC (manual reference counting: manual reference count ). Using Arc reduces the trouble of code and forgetting to release objects. But everything has two sides. If you want to reuse the previously written MRC class after using arc, an er

IOS arc VS mrc learning notes I,* Core Foundation and objective-c Object Exchange * The ARC Management mechanism required for Core Foundation and objective-cObject exchange is as follows: (1) (_ bridge_transfer) op or alternatively CFBridgingRelease (op) is used to consume a retain-count of a CFTypeRef while transferring it over to ARC. This cocould also be represented id someObj =(__bridge ) op; CFRelease(op); (2) (_ bridge_r

Single-instance mode compatible with ARC and MRC, and compatible with arcmrc I. single-instance implementation under ARC Note: The method of user instantiation controls a single execution, while opening the initialization method of the Singleton. -(instancetype)init{ self=[super init]; if(self){ static dispatch_once_t onceToken; dispatch_once(onceToken, ^{ }); } return self; }static id instance; +(ins

that holds a piece of useful data. However, this data is not the only I use in this piece of code, and even many people, in the application of many places. The result is that even if I use this memory, I can't release him, because I'm not sure if someone else needs to use this memory elsewhere. Memory leaks are unavoidable.Memory Management for 1.1.2 OCReference count (Reference count)/retention count (retain count)For a dynamic application of memory, there is a person (pointer) to use, give th

the VC is nil, so it will not be called. That's it. I think VC must be nil, after all I see it destroyed in memory. The Xcode debug in zombie objects hook, re-debug, the results console printed a message sent to deallocated instance 0x90a3900, completely changed my world view! Delegate is not nil .... But my delegate is indeed assign! What is this for? The most fundamental reason is to confuse the weak in arc with the assign in the MRC ....Weak and a

iOS5.0 can start with arc (Automatic Reference counting: Auto reference count) instead of the previous MRC (Manual Reference Counting: Manual reference count). Using arc will reduce the amount of code and the frustration of forgetting to release objects. But there are two sides to everything. After using arc, if you want to reuse a previously written use of the MRC class, you will get an error. What happens

After Xcode5, the new iOS project, the default is the arc mode, but sometimes we need to use some third-party framework in the project, we download and found that is non-arc, this time we need to do arc and MRC mixed. First way, Edit->refactor, convert to Arc modeThe famous iOS network Framework asihttprequest is MRC, we can try to convert to arcClick Check, we found a tragedy.In most cases this is going

After Xcode5, the new iOS project, the default is the arc mode, but sometimes we need to use some third-party framework in the project, we download and found that is non-arc, this time we need to do arc and MRC mixed.The first way:Edit->refactor, convert to Arc modeThe famous iOS network Framework asihttprequest is MRC, we can try to convert to arcClick Check, we found a tragedy.In most cases this is going

1, so you must match 1 release2) only retain when more than 1 people use this objectonly release when burning 1 people to use this object.3) The number of retain to match the number of release4) Never manually invoke the object's Dealloc method, but instead let the system automatically invokeseveral cases of memory leaks in manual memory management:1) Retain and release mismatch, retain excess release caused by memory leaks;2) The object is not used in the process of being release, but is assig

ARC MRC String Memory management strategy research　　Two days ago, arguing with colleagues about whether the nsstring will change after the copy operation, two people to complete a half-day, the last write code verification, found that the original NSString operation is not as simple as we thought, Let's take a look at the NSString and nsmutablestring in the MRC under the Retain,copy,mutablecopy, as well as

iOS5.0 can start with arc (Automatic Reference counting: Auto reference count) instead of the previous MRC (Manual Reference Counting: Manual reference count). Using arc will reduce the amount of code and the frustration of forgetting to release objects. But there are two sides to everything. After using arc, if you want to reuse a previously written use of the MRC class, you will get an error. What happens