Objective-C

The block syntax was added in the iOS4.0 SDK , where more than a dozen APIs were used to block syntax. The block object is also inherited and NSObject, and is a C-language-level syntax and runtime feature . Similar to the standard C function

A copy of an object can be created using the copy or nutablecopy method. The original object is not affected when the copy is modified. Copy : Must be implemented first Nscopying Protocol , Creating an immutable copy (Such as nsstring, nsarray,

// 1. 字典初始化、赋值方式1 NSMutableDictionary *m_dictionary = [[NSMutableDictionary alloc] initWithCapacity:0]; [m_dictionary setObject:@1 forKey:@"语文"]; [m_dictionary setObject:@2 forKey:@"数学"]; [m_dictionary setObject:@3 forKey:@"英语"]; //

// CGPoint 结构体数据原型, 用于声明一个点；/* Points. */ struct CGPoint { CGFloat x; CGFloat y;};typedef struct CGPoint CGPoint; typedef CGPoint NSPoint;// 用法；        // 1. 声明一个CGPoint变量,初始化时赋值方式1；        CGPoint point = {1, 2};  //CGPoint是一个结构体类型，不是对象，所以变量前不加'*'

// Nsvalue can convert the C type to an objective-C object, such as nsange, cgpoint, cgsize, cgrect, cgvector, uiedgeinsets, and uioffset nsange range = nsmakerange (0, 1 ); nsvalue * rangevalue = [nsvalue valuewithrange: range]; // nsvalue converts

Introduction: In the previous article, we talked about KVC. In this article, we learned KVO. The full name is: key value observing. the literal translation is: key value-based observer. So what is its use? KVO is mainly used for view interaction.

Today I learned inheritance, attributes, and polymorphism.   Assignment: Animal parent, cat child, lion and grandson; # Import @ interface animal: nsobject @ end // animal class # import @ interface animal: nsobject @ end // animal class # import "

What is objective-C? Objective-C is (OC ). OC is a superset of C and fully compatible with C language. In addition to the features of C language, it also adds some new features, starting with @, such as @ interface and @ implementation. @ Interface

Block is used to save a piece of code. Block ID: ^Blick is similar to a function. 1. It can save code segments. 2. It has returned values. 3. It has parameters. 4. It has the same calling method. Block definition: Return Value Type (^ block name)

Automatically generated code, not garbage collection Arc judgment criteria: As long as there is no strong pointer to the object, the object will be released   1. Features of Arc -Release, retain, and retaincount cannot be called. -"Dealloc can be

Basic Principles: 1. What is memory management?-The memory of mobile devices is extremely limited, and each app can occupy a limited amount of memory.-When the app occupies a large amount of memory, the system will issue a memory warning, in this

Objective-C has a lot of dynamic features. Basically, it is also often mentioned and used with dynamic types (dynamic typing) and dynamic binding (dynamic binding) and dynamic loading (dynamic loading ). These dynamic features are commonly used in

In objective-C, the method used to call a function is "message transmission". The difference between this method and a common function call is that you can transmit any message to an object at any time, instead of declaring these methods during

Four access controllers of member variables in objective-C: @ PRIVATE: only the current class can be accessed internally. @ Public: All users can access @ Protected: only the current class and its subclass can be accessed. @ Package: allow member

File description: . H class declaration file, the user declares variables, functions (methods) . M class implementation file, the user implements the function (method) in. h)   Class declaration using keywords @ interface, @ end Class implementation

# Import @ interface classvirable: nsobject {nsinteger year; // protect the tree} @ property int age; // setage is available without @ synthesize in the implementation file: and age method-(void) set :( nsinteger) I; @ end #import

OC (objective-C for short) Based on the C language, an object-oriented syntax with the smallest scope is added (the most essential part of object-oriented is retained, and the content of OC is not much java, java does not have much content than C ++,

Struct Nsange:   Used to indicate the range   Create Nsange R1 = {2, 4} Nsange r2 = {. Location = 2,. Length = 4} Nsange R3 = nsmakerange (2, 4)   Search for the range of a string in Str Nsstring * STR = @ "I love OC "; Nsange range = [STR

Reference Counter   When an object is created, it must be allocated to the memory object. When this object is not used, it must be recycled in a timely manner. In order to clearly know whether the object has been used, it must be reflected by the

The code block is essentially similar to other variables. The difference is that the data stored in the code block is a function body. Using code blocks, you can pass in the number of parameters and get the return value just like calling other