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IOS基础 Day-1手动内存管理
辞职回家打算自学IOS开发，就在借个地方记录一下
Day-1 手动内存管理
主要内容:release retain必须配对好，不然会占用内存 慢慢积累导致错误
一旦内存占用超过40m 45m时分别发生警告，一旦超过120m 系统将kill你的app 发生闪退
主要要防止发生的问题:
1.野指针操作
2.内存泄漏
理解retain和assign的区别和 retain的原理
Main
1 // 2 // main.m 3 // 1-1内存管理 4 // 5 // Created by k on 14-8-24. 6 // Copyright (c) 2014年 com.akleee.www. All rights reserved. 7 // 8 9 #import <Foundation/Foundation.h> 10 #import "Person.h" 11 #import "Car.h" 12 void withParam(Person *p) 13 { 14 [p retain]; 15 NSLog(@"withParam : %@ ,retainCount : %lu",p.myName,(unsigned long)[p retainCount]); 16 [p release]; 17 } 18 19 void test1() 20 { 21 Person * p1=[[Person alloc ]init]; 22 23 NSLog(@"retainCount = %lu", (unsigned long)[p1 retainCount]); 24 25 26 p1.myName=@"haha"; 27 28 NSLog(@"p1 : %@",p1); 29 30 Person * p2 = [p1 retain]; 31 32 NSLog(@"retainCount = %lu", (unsigned long)[p1 retainCount]); 33 34 35 p2.myName=@"gaga"; 36 37 NSLog(@"p1 : %@",p1); 38 39 NSLog(@"p2 : %@",p2); 40 41 withParam(p2); 42 43 44 [p2 release]; 45 46 [p1 release]; 47 48 p1=nil; 49 50 NSLog(@"%@",p1);//如果p1！＝nil 则会发生内存泄露 51 52 NSLog(@"%lu", [p1 retainCount]);//nil 但是不报错 53 } 54 55 void test2() 56 { 57 Car * c1=[[Car alloc ] init:@"haha"];//初始化 带参数 的对象 58 59 NSLog(@"%@",c1); 60 61 [c1 release]; 62 } 63 64 void test3(){ 65 Person * p1=[[Person alloc]init:@"ak"]; 66 67 Car * c1= [[Car alloc]init:@"雪弗兰"]; 68 69 [p1 setCar:c1]; 70 71 [p1 run]; 72 73 //1 74 // NSLog(@"p1 retainCount : %lu", [p1 retainCount]); 75 //1 76 //NSLog(@"c1 retainCount : %lu", [c1 retainCount]); 77 78 [c1 release]; 79 80 [p1 release]; 81 } 82 83 void test4() 84 { 85 //测试property的retain 86 Person * p1=[[Person alloc]init]; 87 88 Car * c1=[[Car alloc]init]; 89 90 Car * c2= [[Car alloc]init]; 91 92 NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]); 93 94 95 p1.car=c1; 96 97 98 NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]); 99 100 101 p1.car=c2;102 103 NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);104 105 NSLog(@"c2:%lu",(unsigned long)[c2 retainCount]);106 107 [c1 release];108 [c2 release];109 [p1 release];110 }111 112 void test5()113 {114 Person * p1=[[Person alloc]init];115 116 Car * c1=[[Car alloc]init];117 118 Car * c2= [[Car alloc]init];119 120 //1121 NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);122 //1123 NSLog(@"c2:%lu",(unsigned long)[c2 retainCount]);124 125 126 127 [p1 setCar2:c1];128 129 //2130 NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);131 132 133 [p1 setCar2:c2];134 135 //1136 NSLog(@"c1:%lu",(unsigned long)[c1 retainCount]);137 138 //2139 NSLog(@"c2:%lu",(unsigned long)[c2 retainCount]);140 141 142 143 NSString * s1=@"aaa";144 145 // NSString * s2=@"bbb";146 147 NSLog(@"s1:%lu",(unsigned long)[s1 retainCount]);148 149 [p1 setMyName:s1];150 151 NSLog(@"s1:%lu",(unsigned long)[s1 retainCount]);152 153 [c1 release];154 [c2 release];155 [p1 release];156 157 }158 int main(int argc, const char * argv[])159 {160 161 @autoreleasepool {162 163 // test1();164 // test2();165 // test3();166 test4();167 //test5();168 }169 return 0;170 }
Person.h
1 // 2 // Person.h 3 // 1 基础知识 4 // 5 // Created by k on 14-8-24. 6 // Copyright (c) 2014年 com.akleee.www. All rights reserved. 7 // 8 9 #import <Foundation/Foundation.h>10 #import "Car.h"11 12 @interface Person : NSObject13 @property (nonatomic,assign , readwrite ) NSString * myName ;14 @property (nonatomic,retain,readwrite) Car * car;15 -(instancetype)init:(NSString *) Name;16 -(void) speakMyName;17 -(void)setCar:(Car *) car;18 -(void) run;19 20 21 22 -(void)setCar2:(Car*)car2;23 @end24
person.m
1 // 2 // Person.m 3 // 1 基础知识 4 // 5 // Created by k on 14-8-24. 6 // Copyright (c) 2014年 com.akleee.www. All rights reserved. 7 // 8 9 #import "Person.h"10 11 @implementation Person12 {13 Car * _car2;14 }15 16 - (instancetype)init:(NSString *) Name17 {18 self = [super init];19 if (self) {20 _myName=Name;21 }22 return self;23 }24 25 -(void)speakMyName{26 27 NSLog(@"大家好我的名字叫%@",_myName);28 29 }30 31 32 33 -(void)setCar2:(Car*)car234 {35 if(_car2!=car2)36 {37 [_car2 release];38 _car2=car2;39 [car2 retain ];40 }41 }42 43 -(void)run{44 45 NSLog(@"%@ 驾驶着 %@",_myName,_car.carName);46 47 }48 49 - (NSString *)description50 {51 return [NSString stringWithFormat:@"this is Person,myName=%@", _myName];52 }53 54 - (void)dealloc55 {56 [_car2 release];57 [super dealloc];58 NSLog(@"Person对象被销毁");59 }60 @end
Car.h
1 // 2 // Car.h 3 // 1 基础知识 4 // 5 // Created by k on 14-8-24. 6 // Copyright (c) 2014年 com.akleee.www. All rights reserved. 7 // 8 9 #import <Foundation/Foundation.h>10 11 @interface Car : NSObject12 13 @property (nonatomic,assign,readwrite) NSString * carName;14 - (instancetype)init:(NSString *)Name;15 16 -(void)run;17 @end
Car.m
1 // 2 // Car.m 3 // 1 基础知识 4 // 5 // Created by k on 14-8-24. 6 // Copyright (c) 2014年 com.akleee.www. All rights reserved. 7 // 8 9 #import "Car.h"10 11 @implementation Car12 13 - (instancetype)init:(NSString *)Name14 {15 self = [super init];16 if (self) {17 _carName=Name;18 }19 return self;20 }21 -(void)run22 {23 24 NSLog(@"%@ is Running",_carName);25 }26 - (NSString *)description27 {28 return [NSString stringWithFormat:@"carName : %@", _carName];29 }30 - (void)dealloc31 {32 [super dealloc];33 NSLog(@"Car %@ 被销毁",_carName);34 }35 @end
IOS基础 Day-1手动内存管理
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