x12 isa

First, we will introduce several concepts about the runtime system: (1) ISA pointer: when an object is created, the first element in the memory layout is a pointer to the class structure, that is, Isa. Using the ISA pointer, an object can access its class structure and then access the inherited class structure. (2) SEL data type: it is the environment parameter f

An Introduction to objective-C Meta class First, let's have a look at the base class nsobject. @ Interface nsobject Class ISA; // point to Meta class, all instances of nsobject share the same Meta class. } + (Void) load; + (Void) initialize; -(ID) Init; + (ID) New;+ (ID) allocwithzone :( nszone *) zone;+ (ID) alloc;-(Void) dealloc; + (Class) superclass;+ (Class) class;... @ End Class is defined:Typedef struct objc_class * class;Struct objc_class {Cla

Readme.pam_warnReadme.pam_env Readme.pam_rootok Readme.pam_wheelReadme.pam_filter Readme.pam_securetty Readme.pam_xauth[Email protected] txts]#More Readme.pam_securettyPam_securetty:Allows root logins only if the user was logging in on a"Secure" TTY, as defined by the listing In/etc/securettyAlso checks to make sure That/etc/securetty is a plainFile and not world writable.-Elliot Lee, Red Hat software.July 25, 1996.[Email protected] txts]#More/etc/securettyConsoleVc/1Vc/2Vc/3Vc/4Vc/5Vc/6Vc/7Vc/

), and if you do not delete references to those objects after processing, you can cause an increasing number of unwanted object references in your application. After a program is started, the amount of heap usage is generally constant. As more and more objects are created, the amount of space in the heap becomes more and more, so the usage of the heap increases. The GC reclaims the space occupied by objects that are no longer needed. When a Java program begins to leak memory, the amount of heap

Isa objc_isa_availability;#if!__objc2__Class Super_class objc2_unavailable; Parent classconst char *name objc2_unavailable; Class nameLong version objc2_unavailable; The version information for the class, which defaults to 0Long info objc2_unavailable; Class information for some bit identifiers that are used for the run timeLong Instance_size objc2_unavailable; Instance variable size for this classstruct Objc_ivar_list *ivars objc2_unavailable; The l

). The corresponding function will be called based on the name of the function only when it is actually running.How does OC implement dynamic invocation? Let's take a look at how OC achieves the secret of dynamic calls by sending messages. If you write such a code in OC:1 [obj Maketext];Where obj is an object and Maketext is a function name. For such a simple invocation. Runtime at compile time will convert the above code into1 objc_msgsend (obj, @selector (maketext));First, let's take a look at

Recently, jelly has discovered that several computers in the LAN are infected with viruses and are spreading over the Intranet. These viruses will not only infect machines on the Intranet, but also spread to the Internet, infect machines on the Internet, and the network bandwidth will also be heavily occupied by these viruses, as a result, LAN users cannot access the Internet to work normally. It is difficult to clear these viruses in a short period of time. Therefore, the best practice is to fi

We know that method calls in objective-C are bound at runtime. Further, the compiler will convert the object message [xxx method] To objc_msgsend (ID receiver er, Sel selector, parameter ...) . When we write code, we do not need to use this method directly. This process is converted by the compiler. The dynamic binding process in objc_msgsend is as follows: A. First find its ISA pointer through the aggreger of the first parameter, and then use the sel

objects represent classes, and class objects represent class objects. class Methods belong to class objects. * If the message receiver is a class name, the class name represents the class object. * During runtime, all class instances are generated by class objects. class objects modify the isa value of the instance to their own address, and each instance's isa directs to the Class Object of the instance. *

, represent hue, saturation% and color value, respectively.%% HSV = RGB2HSV(RGB) converts the RGB image RGB (3-D array) to the% equivalent HSV image HSV (3-D array).%% CLASS SUPPORT% -------------% If the input is an RGB image, it can be of class uint8, uint16, or % double; the output image is of class double. If the input is a % colormap, the input and output colormaps are both of class double.% % See also HSV2RGB, COLORMAP, RGBPLOT. % Undocumented syntaxes:% [H,S,V] = RG

respond to messages sent by nstime. So if you want to call the nstime message while sliding the scrollview, we can change the mode of nsunloopNSRunLoopCommonModes4. How does apple implement Autorelease Pool? Autorelease Pool function: cache Pool, which can avoid frequent relase writing. In fact, it is the delayed release, which adds the created object to the latest autoreleasePool. When the scope of autoreleasePool ends, the Reference Counter of all objects in it is-1.AutoreleaseClass Structure

Steps for easymock 1. Generate the mock Interface Iservice mockservice = easymock. createmock ("name", iservice. Class ); To use a mock object instead of an interface, use class Extension: org. easymock. classextension. easymock. If you want multiple mock interfaces, you 'd better use mockcontrol to manage them: Imockscontrol control = easymock. createcontrol (); Iservice1 mockobj1 = control. createmock (iservice1.class ); Iservice2 mockobj2 = control. createmock (iservice2.class );

Http://foredoomed.org/blog/2014/02/24/object-modeling-of-objective-c/ Objective-C is an object-oriented programming language formed by the Smalltalk message mechanism added to C. It is mainly used by Apple to develop Mac OS X and iOS operating systems. Since objective-C is an object-oriented programming language, I am interested in how the object is organized and represented in the memory, and how the message mechanism is implemented.0. nsobject The nsobject class is similar to the object class

Motherboard detection card 1. Tool Introduction The motherboard diagnostic card converts the detection process of the BIOS internal self-check program into code when the motherboard is started. It reads the code displayed on the card and compares it with the fault code table, you can quickly diagnose or locate faults in the main board, memory, CPU, power supply, and other related components. 2. Applicability Suitable for qdi, gigabyte, Microstar and other manufacturers with

Root # make all Root # make install It's easy to connect lm-sensor. Root #/sbin/depmod- Modify the file below to load the function library Root # vi/etc/ld. so. conf /Usr/local/lib add this line Root # ldconfig Root #./prog/mkdev. sh to generate the driver to support what you want to detect Root # sensors-detect: scan the chipset used by your host As long as you press Enter all the time, just wait until the following things come out according to its default value. # ---- Cut here ---- # I2C ada

] { if len (IS) >= $ { NBSP;FO R _, N: = range BS { _ = is[n]//Line 7:bounds check, not smart enough. } }}func fd2 (is []int, BS []byte] { if len (IS) >= $ { NB Sp is = is[:256]//Line 14:bounds check. A hint for the compiler. for _, N: = range BS { _ = is[n]//Line 16:bounds CH Eck eliminatd! } }}func Fe (Isa []int, ISB []int) { if len (ISA) > 0xFFF { nbsp for _, N: = range ISB {

First, in OC about the object model, there are five basic concepts, object (instance), Class (Class), Metaclass (Meta Class), Rootclass (Root Class), Rootclass ' s metaclass (root element Class)Second, each object has a hidden Isa pointer, pointing to class, and the object structure is as follows:typedef struct OBJC_CLASS *class;typedef struct OBJC_OBJECT {Class Isa;} *id;Thirdly, each class structure is as

, respectively.%% HSV = RG B2HSV (RGB) converts the RGB image RGB (Z-array) to the% equivalent HSV image HSV (in-z array). Percent CLASS support%--- ----------% If The input is a RGB image, it can be of class uint8, uint16, or% double; The output image is of class double. If the input is a percent colormap, the input and output colormaps is both of class double.%% see also Hsv2rgb, ColorMap, Rgbplot. % undocumented syntaxes:% [h,s,v] = RGB2HSV (r,g,b) converts the RGB image r,g,b to the% equiva

Python has two ways of formatting strings, using% or using the built-in format () function.Format a string with%Use% in Python to format the string, with a usage and effect similar to% in the C language. The format is:% specific conversion type %data.The following are common types of conversions %s String %d Decimal integer %x hexadecimal integer %o Eight-binary integers %f Decimal floating-point

Runtime is a very interesting thing, if you learn iOS development very often will use or be asked to runtime. So what is runtime and how to get to know it.Runtime: Chinese name runtime, the system in the compilation of some of the types left, the operation in the run time to analyze the dynamic, processing, which also shows that object-c is a dynamic language. (Swift differs from that, although Swift can be called OC's runtime, but Swift itself is a static language.) But by being able to interac