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distribution it's less obvious that you don't have to know whether an object can handle a message before sending it. You send the message to him, he may deal with it, or it may be transferred to another object for processing. A message does not have to correspond to a method, and an object may implement a method to handle multiple messages.At compile time, runtime translates the above code into:Objc_msgsend (obj, @selector (maketext));So actuallyObjc_msgsend (obj, @selector (Maketext)), and is

straightforward and obvious. But for message distribution it's less obvious that you don't have to know whether an object can handle a message before sending it. You send the message to him, he may deal with it, or it may be transferred to another object for processing. A message does not have to correspond to a method, and an object may implement a method to handle multiple messages.At compile time, runtime translates the above code into: Objc_msgsend (obj,@selector (Maketext));

On the question of "runtime mechanism", in order to understand the runtime in depth, first of all, starting from the most basic classes and objects, this article will explain in detail the hierarchy of classes and objects in OC, and the following will gradually update how to use the runtime operation class.First, we find the definition of class and object from/usr/include/objc/objc.h and runtime.h:1 //An opaque type, represents an Objective-c class.2typedefstructObjc_class *Class;3 ///represents

Java garbage collection mechanism.Advantages of 2.2 Objective-cObjective-c language has C + + Java and other object-oriented features, it is far from the advantages of the expression. The advantage of objective-c is that it is dynamic. There are three types of dynamic capabilities:Dynamic class-The runtime determines the object of the classDynamic binding-The runtime determines which method to invokeDynamic load--load a new module for a program at run time2.3 Dynamic capability-related

Java garbage collection mechanism.Advantages of 2.2 Objective-cObjective-c language has C + + Java and other object-oriented features, it is far from the advantages of the expression. The advantage of objective-c is that it is dynamic. There are three types of dynamic capabilities:Dynamic class-The runtime determines the object of the classDynamic binding-The runtime determines which method to invokeDynamic load--load a new module for a program at run time2.3 Dynamic capability-related

1-10 C Language Computer Basics1, please see the following section of codestatic int a = 1;int main(){ int b = 2; char *c = NULL; c = (char *)malloc(100 * sizeof(char)); return 0;} Please visit A,b,c 3 types of variable efficiency from high to low isA. CBAB. ABCC. ACBD. BCAB2. Which of the following four internal sorting algorithms has the highest time complexity in the worst case scenario?A. Quick SortB. Bubble sortC. Heap SequencingD. Merge

Performselector: @selector (introduce::) withobjct:@ "June" withobjct:@ "address"];//delay 2 seconds after call [Stu Performselector: @selector (showname:) withobjct:@ "June" afterdelay:2];Five descriptionNSObject has a description method+ (NSString *) description;When we call NSLog (@ "%@", instance), the description method is called.When customizing a class, you can override this method.Six ReflectionsReflection into classes and methods based on strings1 class ReflectionString class name to c

Algorithm ProgramB) Number of commands in an algorithm programC) storage space occupied by algorithm programsD) storage space required during execution (2) the advantage of using a linked list to represent a linear table isA) convenient Random AccessB) less storage space consumed than sequential StorageC) Easy insert and delete operationsD) The physical sequence of data elements is the same as the logical sequence. (3) In the data structure, data i

unavailable) Do you want to scan it? (YES/no/selectively): YES 3: Do you want to scan the ISA bus? (YES/no): YES 4: Do you want to scan for Super I/O sensors? (YES/no): YES 5: Do you want to scan for secondary Super I/O sensors? (YES/no): YES 6: Now follows a summary of the probes I have just done. Just press ENTER to continue: ENTER 7: I will now generate the commands needed to load the I2C modules. Sometimes, a chip is available both through the

. Although all these operating systems can be used as clients technically, we recommend that you stick to Windows 2000 or Windows XP, because these operating systems support L2TP and PSec protocols. VPN Server The VPN Server can be used as a connection point of the VPN Client. Technically, you can use Windows NT Server 4.0, Windows 2000 Server, Windows Server 2003, and other operating systems as a VPN Server. However, to ensure security, I think you should use the Windows Server 2003 operating

this way, the offset position of the virtual table can be correctly calculated. This allocation is very fast. Only a few pointer operations and a read operation for getting function pointers are required. Objective-C uses the runtime function to enter various types of structures and find the corresponding code for calling.This technology is much slower than the routing of C ++. Objective-C sacrifices a certain amount of speed and security for flexibility and convenience. In C ++, C ++ is very

, 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% equivalent HSV image h,s,v.Percent HSV = RGB2HSV (r,g,b) converts the RGB image r,g,b to the% equivalent HSV image stored in the-Z Array (HSV). [H,s,v] = RGB2HSV (RGB) converts the RGB image RGB (in-array) to% the equiva

Kvc:nskeyvaluecodingKvo:nskeyvalueobserverKVO mechanism: When the property of the specified object changes, it proactively notifies another object and triggers the appropriate method.Whenever a listener is defined in a class:[Self addobserver:selfforkeypath:@ "Items" options:0 context:contexstr];You can also listen for changes to the properties of other objects[Person Addobserver:money forkeypath:@ ' account ' options:0 context:contexstr];Only the changes to the Items property in the current cla

. The options are 250, 500, 750, and 1 000, in milliseconds. (14) security option: When system is selected, the system will prompt you to enter the password each time the server is started. When setup is selected, the system will prompt you to enter the password only when entering c mos setup. (15) PS/2 mouse function control: when this item is set to enable, the machine provides support for the PS/2 type mouse. Otherwise, select disable. (16) Assign pci irq for VGA: When enable is selected,

* strClass = NSStringFromClass ([Person class]);2 method reflection// String method name to method NSString * funName = @ "go"; SEL selector = NSSelectorFromString (funName); [stu performSelector: selector]; // method to string method name NSString * strFun = NSStringFromSelector (selector );NSObject nature@interface NSObject { Class isa;} We can see that the NSObject object only has one member variable Class

the external ISP. In terms of client efficiency, the first method is better; but in terms of controllability and scalability, as well as network efficiency, the second method is better, especially for environments with a domain, the second method must be used for DNS forwarding. Kwf has a DNS forwarder, which is more efficient than Windows DNS servers. It only supports DNS forwarding. ISA does not have a DNS forwarder. However, using the full-feature

error.) C language will be in the compilation phase error). 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:[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 intoObjc_msgsend (

object to be observed (for example, a), and when a property of an object (such as the string name in a) changes, the object is notified and processed accordingly; "and you don't need to add any extra code to the object being observed, you can use the KVO mechanism" Under the MVC Design Architecture project, the KVO mechanism is well suited for communicating between the mode model and view views.For example: In the code, create the attribute data in model Class A, create the observer in the

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