5、内存管理（自定义MyArray）-OC

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站在数组上，看怎来使用retain、release

（1）了解NSMutableArray如何实现

（2）进一步深入内存管理

（1）了解NSMutableArray如何实现

NSMutableArray *array = [[NSMutableArray alloc] init];

for(int i=0;i<10;i++)
{
Dog *dog = [[Dog alloc] init];
[dog setID:i];
[array addObject:dog];//里面有用到retain引用，所以dog计数器会变成2
[dog release];//所以这个dog没有释放
}

for(Dog *d in array)
{
NSLog(@"dog is %d",[d ID]);
}

[array release];//将数组中所有的dog 和 array 释放掉

实现数组提供的方法：
（1）(void)addObject:(id)object;
（2）(id) objectAtIndex:(NSUInteger)index;
（3）(void) removeObjectAtIndex:(NSUInteger)index;
（4）(void)removeAll;

（2）进一步深入内存管理

//视频5 main.m#import <Foundation/Foundation.h>#import "Dog.h"int main( int argc, const char * argv[] ){@autoreleasepool{#if0NSMutableArray * array = [[NSMutableArray alloc] init];for(int i=0;i<10;i++){Dog *dog = [[Dog alloc] init];NSLog(@"dog retainCount is %ld\n",[d retainCount]);[dog setID:i];[array addObject:dog];//里面有用到retain引用，所以dog计数器会变成2NSLog(@"dog retainCount is %ld\n",[d retainCount]);[dog release];//所以这个dog没有释放}for(Dog *d in array){NSLog(@"dog is %d",[d ID]);}[array release];//将数组中所有的dog 和 array 释放掉#endifMyArray * array = [[MyArray alloc] init];for(int i=0;i<10;i++){Dog *dog = [[Dog alloc] init];NSLog(@"dog retainCount is %ld\n",[d retainCount]);[dog setID:i];[array addObject:dog];//里面有用到retain引用，所以dog计数器会变成2NSLog(@"dog retainCount is %ld\n",[d retainCount]);[dog release];//所以这个dog没有释放}[array release];}return 0;}

//Dog.h#import <>@interface Dog : NSObject{int _ID;}@property (assign) int ID;@end

//Dog.m#import "Dog.h"@implementation Dog@synthesize ID=_ID-（void） dealloc{NSLog(@"dog is %d dealloc\n",_ID);[super dealloc];}@end

//MuArray.h#import <>@interface MyArray: NSObject{NSUInteger _count;//数组当前有几项元素,是一个整数id _objs[512];//创建一个512的数组，有4x512字节}@property (assign, readonly) NSUInteger count;//往MyArray加入一项元素- (void)addObject:(id)object;//取得第index项元素- (id) objectAtIndex:(NSUInteger)index;//删除第index项元素- (void) removeObjectAtIndex:(NSUInteger)index;//删除所有元素- (void)removeAll;@end

//MuArray.m#import "Dog.h"@implementation Dog@synthesize count = _count;- (id) init{self = [super init];if(self){_count = 0;}return self;}//往MyArray加入一项元素- (void)addObject:(id)object{if(_count >= 512)return;_objs[_count] = [object retain];_count ++;//这里必须要做[object retain]}//取得第index项元素- (id) objectAtIndex:(NSUInteger)index{return _objs[index];}//删除第index项元素- (void) removeObjectAtIndex:(NSUInteger)index{id obj = _objs[index];[obj release];_objs[index] = nil;}//删除所有元素- (void)removeAll{for(int i=0;i<_count;i++){[self removeObjectAtIndex:i];}}-（void） dealloc{[self removeAll];NSLog(@"remove all\n");[super dealloc];}@end

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