IOS之學(xué)習(xí)筆記五(合成存取方法)

一、主要屬性介紹

1、自動(dòng)合成setter、getter方法

1)、接口部分@property指定屬性  2)、實(shí)現(xiàn)部分@synthesize

如果

@syntheszie  widows = _windows

這里成員變量名是_windows,而不是windows


2、atomic(nonatomic)

這里主要是指存取方法為原子操作，實(shí)現(xiàn)線程安全，atomic是默認(rèn)，保證線程安全，但是會(huì)導(dǎo)致性能降低，單線程我們一般考慮nonatomic


3、copy

用這個(gè)修飾了屬性名，把副本值設(shè)置給類(lèi)的屬性，如果賦值的副本發(fā)生改變，但是類(lèi)部的屬性值不會(huì)改變


4、getter、setter

如果(getter = ff1, setter = ff2)，會(huì)把默認(rèn)的getter方法改為ff1, 會(huì)把默認(rèn)setter方法改為ff2,我們調(diào)用的時(shí)候就是[對(duì)象 ff1]、[對(duì)象 ff2]


5、readonly、readwirte

readonly是指系統(tǒng)指合成getter方法，不合成setter方法

readwirte是默認(rèn)的，都合成


6、retain

使用retain指示定義屬性時(shí)，當(dāng)莫個(gè)對(duì)象賦值給屬性時(shí)，該屬性原來(lái)所引用的對(duì)象引用計(jì)數(shù)減1，被賦值對(duì)象的引用計(jì)數(shù)加1

當(dāng)一個(gè)對(duì)象的引用計(jì)數(shù)大于1時(shí)，該對(duì)象不該被回收。


7、strong、weak

strong:指被賦值對(duì)象持有強(qiáng)引用，不會(huì)自動(dòng)回收

weak:使用弱引用指向被賦值對(duì)象，該對(duì)象可能被回收


 
二、測(cè)試demo

User.h

    #ifndef User_h
    #define User_h
    #import <Foundation/Foundation.h>
    @interface User : NSObject
    @property (nonatomic) NSString *name;
    @property (nonatomic) NSString *city;
    @property (nonatomic, copy) NSString *add;
    @property NSString *pass;
    @property NSDate *birth;
    @property NSDate *birth1;
    @end
    #endif /* User_h */

 User.m

    #import <Foundation/Foundation.h>
    #import "User.h"
     
    @implementation User
    @synthesize name = _name;
    @synthesize pass;
    @synthesize  birth;
    -(void) setName:(NSString *)name
    {
        self->_name = [NSString stringWithFormat:@"hello%@", name];
    }
    @end

main.m文件

    #import <UIKit/UIKit.h>
    #import "AppDelegate.h"
    #import "Person.h"
    #import "Apple.h"
    #import "User.h"
    #import "Args.h"
    #import "KVCPerson.h"
     
    int main(int argc, char * argv[]) {
        @autoreleasepool {
            
            
            User *user = [User new];
            NSMutableString *name = [NSMutableString stringWithString:@"chencaifeng"];
            NSMutableString *city = [NSMutableString  stringWithString:@"hunan"];
            NSMutableString *addr = [NSMutableString stringWithString:@"luyunlu"];
            [user setName:name];
            [user setCity:city];
            [user setAdd:addr];
            [user setPass:@"hello"];
            [user setBirth:[NSDate date]];
            NSLog(@"name is %@, and pass is %@, birth is%@, city is%@, add is %@", [user name], [user pass], [user birth], [user city], [user add]);
            //我們把setName函數(shù)重寫(xiě)了，雖然name后面追加了字符串，但是后面打印值沒(méi)有改變
            [name appendString:@"chenyu"];
            //由于這里屬性沒(méi)有加copy，city后面追加了字符串，所以后面打印也變了
            [city appendString:@"changsha"];
            //由于這里屬性加了copy,由于這個(gè)addr后面值追加了，所以后面打印不會(huì)改變
            [addr appendString:@"kanyunlu"];
            NSLog(@"name is %@, and pass is %@, birth is%@, city is%@, add is %@", [user name], [user pass], [user birth], [user city], [user add]);
            
            //這里是用.操作
            user.add = @"hello";
            NSLog(@"user add is %@", user.add);
        }
    }


三、運(yùn)行結(jié)果

    name is hellochencaifeng, and pass is hello, birth isFri Jul  6 19:51:04 2018, city ishunan, add is luyunlu
    name is hellochencaifeng, and pass is hello, birth isFri Jul  6 19:51:04 2018, city ishunanchangsha, add is luyunlu
    user add is hello

 




 


作者：chen.yu
深信服三年半工作經(jīng)驗(yàn)，目前就職游戲廠商，希望能和大家交流和學(xué)習(xí),
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