看看下面的程序有什么问题：

BNRItem.h

@interface BNRItem : NSObject@property (nonatomic, strong) BNRItem *containedItem;@property (nonatomic, strong) BNRItem *container;...@end

 

BNRItem.m

#import "BNRItem.h"@implementation BNRItem...- (void)setContainedItem:(BNRItem *)containedItem{    _containedItem = containedItem;    self.containedItem.container = self;}@end

main.m

int main(int argc, const char * argv[]){    @autoreleasepool {        // Create a mutable array object, store its address in items variable        NSMutableArray *items = [[NSMutableArray alloc] init];        BNRItem *backpack = [[BNRItem alloc] initWithItemName:@"Backpack"];        [items addObject:backpack];        BNRItem *calculator = [[BNRItem alloc] initWithItemName:@"Calculator"];        [items addObject:calculator];        backpack.containedItem = calculator;        backpack = nil;        calculator = nil;        for (BNRItem *item in items) {            NSLog(@"%@", item);        }        // Destroy the mutable array object        NSLog(@"Setting items to nil...");        items = nil;    }    return 0;}

 

上面的程序是有问题的，会导致循环引用(strong reference cycle)。

导致内存泄露。

 

解决方案:

将某个指针的特性设置为弱引用

@property (nonatomic, weak) BNRItem *container;