如何解决内存泄漏周期

Question

How can I solve this kind memory leak problem? Please help.

@interface ParseOperation () <NSXMLParserDelegate>
// Redeclare appRecordList so we can modify it.
@property (nonatomic, strong) NSArray *appRecordList;
@property (nonatomic, strong) NSData *dataToParse;
@property (nonatomic, strong) NSMutableArray *workingArray;
@property (nonatomic, strong) AppRecord *workingEntry;
@property (nonatomic, strong) NSMutableString *workingPropertyString;
@property (nonatomic, strong) NSArray *elementsToParse;
@property (nonatomic, readwrite) BOOL storingCharacterData;
@end

Answer 1

You can either autorelease:

if ([elementName isEqualToString:kEntryStr]) {
    self.workingEntry = [[[AppRecord] new] autorelease];
}

or simply release:

if ([elementName isEqualToString:kEntryStr]) {
    self.workingEntry = [[AppRecord] new];
    [self.workingEntry release];
}

By the way, new is same as alloc + init.

Answer 2

由于ARC已禁用，因此您需要在创建AppRecord实例时自动释放它。

self.workingEntry = [[[AppRecord alloc] init] autorelease];

Answer 3

First of all it's not a retain circle, it's just memory leak.

Leak

In your situation workingEntry is strong property. That mean, that setter of workingEntry is something like:

- (void)setWorkingEntry:(AppRecord *)workingEntry {
    if (workingEntry != _workingEntry){
        [_workingEntry release];
        _workingEntry = [workingEntry retain];
    }
}

As you can see after setWorkingEntry: property will have retainCounter at least 1, that will be decreased in dealloc by [_workingEntry release]; and in normal case retain counter should be 0 to free that instance, but in you case you set [[AppRecord alloc] init] (that also have +1 retain counter). So in this case in dealloc you will have _workingEntry with retain counter = 2, after you release it, retain counter will became = 1 and will never be freed. So release in after setting to make retain counter normalized:

if ([elementName isEqualToString:kEntryStr]) {
    self.workingEntry = [[AppRecord] new]; // or [[AppRecord alloc] init]
    [self.workingEntry release];
}

Retain circle

Retain circle occurs when two (or more) objects have strong references to each other, and that links released, for example, in deallocs of that classes. In such situation they will never be released, because there will be at least one strong link to them at any moment (from other object, that also can't be freed).