The difference between the @property and Ivar of IOS Basics _ios

@property

A property is actually an encapsulation of a member variable. Let's think about this first:

@property = Ivar + setter + getter

Ivar

Ivar can be understood as a variable in a class, and the primary role is to save data.

Let's take a look at an example, and we can explain these two things clearly by using the example below:

We create a new person class

@interface person:nsobject
{
nsstring *NAME0;
}
@property (nonatomic,copy) nsstring *name1;
@end
@implementation Person
-(instancetype) init {
if (self = [super init]) {
} return
self;< c15/>}
@end

In this person NAME0 is the member variable, name1 is the attribute.

We create a person:

Person *p= [[Person alloc] init];
p.name1 = @ "abc";
NSLog (@ "%@", p.name1);

What does it mean that I can't access NAME0 outside of the person class? This indicates that the member variable <font color=red>name0</font> can only be accessed inside its own class.

Therefore, we infer that @property actually has interface properties, that is, can be accessed by external objects.

p.name1 = @ "abc";

This line of code is actually a setter method that invokes the name1 in person.

NSLog (@ "%@", p.name1);

This line of code is actually the Getter method that invokes the name1 in person.

Again, the setter and getter methods. We should all know that OC has a strict naming code, take this example, according to NAME1 automatically generated

-(void) setName1: (NSString *) name1{}
-(NSString *) name1

Note: The MRC is not discussed here, and all explanations are provided under arc.

@synthesize

This keyword is used to specify the member variable

In the implementation of person, we change the code to this way:

@implementation person
@synthesize name1 = _name2;
-(Instancetype) init {
if (self = [super init]) {
_name2 = @ "AAA";
}
return self;
}
@end

This allows us to specify that the NAME1 member variable is _name2, and we cannot _name1 this attribute at all in the initialization init method of person.

Person *p= [[Person alloc] init];
p.name1 = @ "abc";
NSLog (@ "%@", p.name1);

We comment out the assigned line and we can see that the printout is: AAA.

The above is a small set to introduce the iOS basic knowledge of the @property and Ivar differences, I hope to help you, if you have any questions please give me a message, small series will promptly reply to everyone. Here also thank you very much for the cloud Habitat Community website support!