在 ARC 中收到内存警告
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【中文标题】在 ARC 中收到内存警告【英文标题】：Received Memory Warning in ARC 【发布时间】：2014-01-08 08:34:09 【问题描述】：我正在调用 syncWithCalendar，在成功添加事件后，我收到内存不足警告，并且应用程序因“收到内存不足”警告而终止。日历中生成和保存的事件超过 50 个。我尝试使用工具，但无法找到发生内存泄漏的代码，也无法通过工具中显示的实时字节找到导致泄漏。谁能帮我解决这个问题。
- (void)syncWithCalendar
@autoreleasepool
[self deleteEventsIfExist];
NSMutableDictionary *dictionary = [util readPListData];
NSMutableArray *courses = [util getCourses];
__block NSMutableArray *lessons;
__block NSMutableDictionary *lesson;
NSString *studentID = [util getProgramDetails].studentId;
NSString *programName = [util getProgramDetails].programName;
double offset[] = 0, 0, -300, -900, -1800, -3600, -7200, -86400, -172800;
__block NSString *startDateString = @"", *endDateString = @"";
NSTimeInterval relativeOffsetValue = 0;
int index = [[dictionary objectForKey:@"event-alert-option"] intValue];
relativeOffsetValue = offset[index];
NSDateFormatter *formatter;
formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MM/dd/yyyy HH:mm:ss"];
[formatter setDateFormat:@"MM/dd/yyyy"];
NSString *currentDateString = [NSString stringWithFormat:@"%@ 09:00:00", [formatter stringFromDate:[NSDate date]]];
[formatter setDateFormat:@"MM/dd/yyyy HH:mm:ss"];
NSDate *currentDate = [formatter dateFromString:currentDateString];
EKEventStore *eventStore = [[EKEventStore alloc] init];
if([eventStore respondsToSelector:@selector(requestAccessToEntityType:completion:)])
// ios 6 and later
[eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error)
if (granted)
//---- codes here when user allow your app to access theirs' calendar.
dispatch_async(dispatch_get_main_queue(), ^
// Event creation code here.
for (int i=0; i<[courses count]; i++)
@autoreleasepool
lessons = [[courses objectAtIndex:i] objectForKey:@"lessons"];
for (int j=0; j<[lessons count]; j++)
@autoreleasepool
lesson = [lessons objectAtIndex:j];
NSString *title = nil;
title = [NSString stringWithFormat:@"%@ %@-Complete %@ lesson",studentID,programName,[lesson objectForKey:@"lesson-name"]];
if ([[lesson objectForKey:@"actual-exam-date"] isEqualToString:@"00/00/0000"])
startDateString = [NSString stringWithFormat:@"%@ %@", [lesson objectForKey:@"plan-exam-date"], @"09:00:00"];
endDateString = [NSString stringWithFormat:@"%@ %@", [lesson objectForKey:@"plan-exam-date"], @"18:00:00"];
else
if ([[lesson objectForKey:@"retake-actual-date"] isEqualToString:@"00/00/0000"])
startDateString = [NSString stringWithFormat:@"%@ %@", [lesson objectForKey:@"retake-plan-date"], @"09:00:00"];
endDateString = [NSString stringWithFormat:@"%@ %@", [lesson objectForKey:@"retake-plan-date"], @"18:00:00"];
if (!([startDateString isEqualToString:@""] && [endDateString isEqualToString:@""]))
EKEvent *event = [EKEvent eventWithEventStore:eventStore];
event.title=title;
event.startDate = [formatter dateFromString:startDateString];
event.endDate = [formatter dateFromString:endDateString];
event.allDay = NO;
if (index != 0)
event.alarms = [NSArray arrayWithObjects:[EKAlarm alarmWithRelativeOffset:relativeOffsetValue], nil];
[event setCalendar:[eventStore defaultCalendarForNewEvents]];
// Compare current date to event start date, if start date has been passed then preventing to sync with calendar
NSComparisonResult result = [event.startDate compare:currentDate];
if (result != NSOrderedAscending)
NSError *err = nil;
[eventStore saveEvent:event span:EKSpanThisEvent commit:YES error:&err];
if (err)
NSLog(@"event not saved .. error = %@",err);
else
NSLog(@"event added successfully");
// autoreleasepool
// lessons for loop
// autoreleasepool
// courses for loop
[self hideModal];
);
else
//----- codes here when user NOT allow your app to access the calendar.
// [self performSelectorOnMainThread:@selector(hideModal) withObject:nil waitUntilDone:NO];
];
else
// sync calendar for <iOS6
// autoreleasepool
- (void)deleteEventsIfExist
@autoreleasepool
NSMutableArray *courses = [util getCourses];
__block NSMutableArray *lessons;
__block NSMutableDictionary *lesson;
NSString *studentID = [util getProgramDetails].studentId;
NSString *programName = [util getProgramDetails].programName;
EKEventStore* store = [[EKEventStore alloc] init];
dispatch_async(dispatch_get_main_queue(), ^
// Event creation code here.
NSDate* endDate = [NSDate dateWithTimeIntervalSinceNow:[[NSDate distantFuture] timeIntervalSinceReferenceDate]];
NSPredicate *fetchCalendarEvents = [store predicateForEventsWithStartDate:[NSDate date] endDate:endDate calendars:store.calendars];
NSArray *allEvents = [store eventsMatchingPredicate:fetchCalendarEvents];
for (int i=0; i<[courses count]; i++)
@autoreleasepool
lessons = [[courses objectAtIndex:i] objectForKey:@"lessons"];
for (int j=0; j<[lessons count]; j++)
@autoreleasepool
lesson = [lessons objectAtIndex:j];
NSString *oldEventSubtitle = [NSString stringWithFormat:@"%@ %@-Complete %@ lesson",studentID,programName,[lesson objectForKey:@"lesson-name"]];
for (EKEvent *e in allEvents)
if ( [oldEventSubtitle isEqualToString:e.title])
NSError* error = nil;
[store removeEvent:e span:EKSpanThisEvent commit:YES error:&error];
NSLog(@"deleting events");
// autoreleasepool
// lessons
// autoreleasepool
// courses
);
// autoreleasepool
【问题讨论】：
问题可能出在您的util 电话中。您正在阅读整个 plist，然后将其他数据放入变量中（可能是多余的）。不要在这里转储你的代码。想想问题可能出在哪里，然后发布选择性代码。
仪器至少应该向您展示分配大量内存的“热点”。你能发布 Instruments 视图吗？
@Mundi 但我正在阅读 plist 一次。你说的冗余是什么意思。除了我使用这两个函数时，应用程序在所有其他情况下都运行良好，所以我认为问题可能只出在这两个函数上。
@CouchDeveloper 我尝试发帖，但它说我需要至少 10 个声望才能发帖。我有 9 名声望，但在发布此问题后，我猜我的声望降至 3。现在我猜我无法发布图片了。
@CouchDeveloper drive.google.com/file/d/0ByegeKbbsr95SGQ3dG93azc1VVE/…
【参考方案1】：
这是一个粗略的猜测，但似乎异步调用可能会导致麻烦。
为了测试这一点，只需使用dispatch_sync 而不是dispatch_async 并检查内存消耗。如果这会带来改进，那么解决方案就在眼前，这涉及重构您当前的异步“并行”方法并将其转变为适当的异步“串行”方法或完整的同步方法。
这可能还需要“序列化”此异步方法的所有调用：
[eventStore requestAccessToEntityType:EKEntityTypeEvent
completion:^(BOOL granted, NSError *error)
...
]
【讨论】：
【参考方案2】：这就是我调用syncWithCalendar函数的方式
if([eventStore respondsToSelector:@selector(requestAccessToEntityType:completion:)])
// iOS 6 and later
[eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted,
NSError *error)
if (granted)
dispatch_async(dispatch_get_main_queue(), ^
[self syncWithCalendar];
);
else
// calendar access not granted
];
在syncWithCalendar 函数中，除了代码行之外，一切都保持不变
正在创建崩溃/内存问题。下面是我错误的代码行
早点使用
// wrong
[self.eventstore saveEvent:event span:EKSpanThisEvent commit:YES error:&err];
保存事件的正确方法：（注意：在我的例子中我不需要事件标识符）
// correct
[self.eventstore saveEvent:event span:EKSpanThisEvent commit:NO error:&err];
然后在保存所有事件后使用[self.eventstore commit:NULL]。在我的情况下，这停止了崩溃。希望这篇文章会
帮助其他人获得解决方案。谢谢！！！！
【讨论】：
【参考方案3】：当你收到内存警告时，你需要清除缓存，使用这个方法会帮助你。
-(void)applicationDidReceiveMemoryWarning:(UIApplication *)application
[[NSURLCache sharedURLCache] removeAllCachedResponses];
【讨论】：
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