是什么导致iOS内存泄漏

我知道以前有人问过这个问题，但我不确定它在我的场景中是如何应用的。使用仪器，我发现了一个内存泄漏，但我不知道如何纠正这个泄漏。泄漏发生在

OSStatus状态

行

// Set up a query dictionary with the base query attributes: item type (generic), username, and service
NSArray *keys = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClass, kSecAttrAccount, kSecAttrService, nil];
NSArray *objects = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClassGenericPassword, username, serviceName, nil];
NSMutableDictionary *query = [[NSMutableDictionary alloc] initWithObjects: objects forKeys: keys];
// First do a query for attributes, in case we already have a Keychain item with no password data set.
// One likely way such an incorrect item could have come about is due to the previous (incorrect)
// version of this code (which set the password as a generic attribute instead of password data).
NSMutableDictionary *attributeQuery = [query mutableCopy];
[attributeQuery setObject: (id) kCFBooleanTrue forKey:(__bridge_transfer id) kSecReturnAttributes];
CFTypeRef attrResult = NULL;
OSStatus status = SecItemCopyMatching((__bridge  CFDictionaryRef) attributeQuery, (CFTypeRef *) &attrResult); <--- Here is the leak
NSLog(@"SFHFKeychainUtils => getPasswordForUsername => status => %d\n", status);
NSLog(@"SFHFKeychainUtils => getPasswordForUsername => attrResult => %@\n", attrResult);
NSLog(@"SFHFKeychainUtils => getPasswordForUsername => attributeQuery => %@\n", attributeQuery);
if (status != noErr) {
    // No existing item found--simply return nil for the password
    if (error != nil && status != errSecItemNotFound) {
        //Only return an error if a real exception happened--not simply for "not found."
        *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];
    }
    return nil;
}

//使用基本查询属性设置查询字典：项类型（通用）、用户名和服务
NSArray*键=[[NSArray alloc]initWithObjects:（uu桥u传输NSString*）kSecClass，kSecAttrAccount，kSecAttrService，nil]；
NSArray*对象=[[NSArray alloc]initWithObjects:（\uuu bridge\u transfer NSString*）kSecClassGenericPassword，username，serviceName，nil]；
NSMutableDictionary*query=[[NSMutableDictionary alloc]initWithObjects:objects-forKeys:keys]；
//首先查询属性，以防我们已经有一个没有密码数据集的Keychain项。
//这种不正确的项目可能产生的一种方式是由于之前的（不正确的）
//此代码的版本（将密码设置为通用属性而不是密码数据）。
NSMutableDictionary*attributeQuery=[query mutableCopy]；
[attributeQuery setObject:（id）kCFBooleanTrue forKey:（_bridge_transfer id）kSecReturnAttributes]；
CFTypeRef attrResult=NULL；
OSStatus status=SecItemCopyMatching（（uu桥CFDictionaryRef）attributeQuery，（CFTypeRef*）和attrResult） 
SecItemCopyMatching
将属性复制到
attrResult

由于您有一份副本，您有责任在某个时候发布它，包括：

CFRelease(attrResult)

这些都在
SecItemCopyMatching
中描述，它将属性复制到
attrResult

由于您有一份副本，您有责任在某个时候发布它，包括：

CFRelease(attrResult)

这一切都在报告中描述过