Objective C attribute keyword

Two ways to access and assign member variables ：

One .get set The way

@interface Person : NSObject{
    // Member variables 
    NSString* _name;
}
-(void)setName:(NSString*)name;
-(NSString*)name;
@end

#import <Foundation/Foundation.h>
#import "Person.h"


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Person* p1 = [Person new];
        [p1 name];
        [p1 setName:@"dancer"];
        
    }
    return 0;
}

Two . Attribute mode

[email protected](strong, nonatomic)

@interface Person : NSObject{
    // Member variables 
    NSString* _name;
}
// attribute 
@property(strong, nonatomic)NSString* name;
@end

#import <Foundation/Foundation.h>
#import "Person.h"


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Person* p1 = [Person new];
        p1.name = @"dancer";
        NSString* name = p1.name;
        NSLog(@"name = %@",name);
    }
    return 0;
}

2. Statement property Statement synthesize

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface Person : NSObject{
    NSInteger _age;
}
// attribute 
@property(assign, nonatomic)NSInteger age;
@end

NS_ASSUME_NONNULL_END

#import "Person.h"

@implementation Person

@synthesize age;

@end

3. Omit attribute method of member variable

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface Person : NSObject{
    NSInteger _age;
}
// attribute 
@property(strong, nonatomic)NSString* name;
@property(assign, nonatomic)NSInteger age;
// No corresponding member variable can automatically generate a private member variable  _ Property name 
@property(assign, nonatomic)NSInteger weight;
@end

NS_ASSUME_NONNULL_END

Use synthesize Modify the name of the automatically generated member variable

#import "Person.h"

@implementation Person

@synthesize age;
// Use synthesize Modify the name of the automatically generated member variable 
@synthesize  weight = _myWeight;
@end