Objective-C

Under MacOS, you can use the Authorizationexecutewithprivileges function to run a program as an administrator, which will pop up a box to enter a password if run with administrator privileges. And the execution of this program if the administrator

objective-locks and applications in C in multithreaded programming, locks are a very important tool, and objective-C provides several different types of locks, so let's look at how these locks are used. 0. POSIX Mutex Lockmutex Lock is also a mutex,

　　A method may have more than one input parameter. In a header file, you can define a method with multiple input parameters:-(void) Setintx: (int) n andsetinty: (int) dHere is an example of how to use it:　　1 #import2 3 @interfacetest:nsobject{4

Definition and use of the Protocol What is an agreement?Can be used to declare a whole bunch of methods (cannot declare member variables)As long as a class follows this protocol, it is equivalent to having all the method declarations in this

The first thing to mention here is the copy in the attribute list where the attribute is defined@property (nonatomic,copy) NSString *name;Here I define a person class, which is no longer stated hereHere is the codePerson *p = [[Person alloc]

//Dictionary: (keyword value)Insert code word is too smallNsarray *array = [Nsarray array];//empty arrayNsdictionary *dictionary = [Nsdictionary dictionary];//empty DictionaryNsdictionary *my = [nsdictionary dictionarywithobject:@ "objective" forkey:

1 ifMrhiggieismean = NO; if (Mrhiggieismean) { NSLog (@ "confirmed:he is super mean");}2 if ElseBOOL Mrhiggieismean = [Mrhiggie Areyoumean]; if (Mrhiggieismean) { NSLog (@ "confirmed:he is super mean");} Else { NSLog (@ "No, actually he ' s

Access permissions for member variablesThe member variables in OBJECTIVE-C have the following three properties Public (external and sub-class accessible) Protected (sub-class accessible, externally inaccessible) Private (external

Objective-c Five main features: Fully compatible with C Object oriented Single Inheritance (functions in OC are virtual functions, pseudo-Multiple inheritance through classes and protocols) Dynamic binding (when dynamic_cast

Like the closure in JS, anonymous functions in Java, C # delegates, you can pass Func as a parameter:Statement of the 1.BlockThe definition of block is similar to the declaration of a function, which is to change the function name to (^blockname).

Method One:NSString *str = @ "ABCDEFG";nsmutablestring *reversestring = [nsmutablestring string];for (int i = str.length-1; I >= 0; i--) {char c = [Str characteratindex:i];[ReverseString appendformat:@ "%c", c];}NSLog (@ "%@", reversestring);Results:

Directory of this document I. Open Xcode and create a new Xcode project Two. Select the simplest command line item Three. Enter the project name and select the foundation framework to create the project Four, click Run, running the

Category: Adding new methods to known classes; extension: Notifications use classes to declare private methods in the definition of this class;I. Category:1. Application of the class method: To extend an existing class: for example, you can

Nsinteger is not an object, converted to a long match 64-bit system, and then composed of a string (%LD).NSString *inStr = [NSString stringWithFormat: @"%ld", (long)month];Note that on 64-bit processors, such as the new A7 chip, if your app was

NSObject Common methodsUsed to determine whether a method is implemented in an object (encapsulated in a selector object)-(BOOL) respondstoselector:selector//used to determine whether a method is implemented in an object. The difference between

Initialize object allocation memory + (ID) alloc; The birth of an object is essentially a large enough memory from the operating system to hold all the instance variables of the class and designate it as the location of the instance

Deep copy and shallow copy shallow copy Shallow copy (shallow copy) feature: The referenced object is not copied, its newly copied object is just a pointer to an existing reference object. (It's actually the equivalent of a shortcut copy

Directory (?) [-] Have one of the same two different same Written by Mattt Thompson on Dec 10th 2012 What's a instancetype? Two associative return types related result types Three instancetype effect Role

In fact, with the C language and Java,oc is also a switch multi-branch statements, can also be called switch statements. The syntax is also very similar. Let's take a slow look at switch.(a) Code one:int main (int argc, const char * argv[]) {

After the Objective-c object receives the message, what method is called to be resolved during runtime. Then you might ask: Does the method corresponding to the given selection sub-name change at runtime? Yes, that's it. Using this feature can be a