我试图在应用程序终止时通过NSURLSession进行快速POST.应用程序终止定义为用户在主屏幕上将其滑出.此外,applicationWillTerminate被示范性地调用(因此不存在问题).
我的目的是通知服务器该用户现在正在脱机.
但是,这不起作用..因为我的后端没有收到POST.我想弄清楚为什么这不起作用..或者即使它应该？根据Apple文档,这应该可以工作,如果它可以在5秒内执行..虽然我甚至没有完成处理程序,所以它应该被执行.任何帮助或建议将不胜感激.
我的实现如下(供参考).
- (void)applicationWillTerminate:(UIApplication *)application {
NSMutableDictionary * gatherAllInputs = [[NSMutableDictionary alloc] initWithObjectsAndKeys:
@"blah@df.com, @"emailEntry",
@"False", @"isPersonAvailable",
nil];
NSError *error;
NSData *gatherAllInputsJSON = [NSJSONSerialization dataWithJSONObject:gatherAllInputs options:0 error:&error];
NSString* theDataSentToServer;
theDataSentToServer = [[NSString alloc] initWithData:gatherAllInputsJSON encoding:NSUTF8StringEncoding];
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *postingSession = [NSURLSession sessionWithConfiguration:sessionConfiguration];
NSURL *url = [NSURL URLWithString:@"https://blahblahblah.com/someblah"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"POST"];
[request setHTTPBody:[theDataSentToServer dataUsingEncoding:NSUTF8StringEncoding]];
NSURLSessionDataTask *postSomething = [postingSession dataTaskWithRequest:request];
[postSomething resume];
NSLog(@"Got here!"); //<-- THIS GETS OUTPUTTED.. SO I KNOW THIS CODE …我遇到了一些麻烦,我想知道是否有人可以提供一些指导.
我试图按以下顺序创建节标题:["推","忙","完成","取消"].
不幸的是,这个订单无法通过简单的"升序YES/NO"来实现......我必须添加一个自定义比较选择器......这样的事情......:
**"状态"映射到["推","忙","完成","取消"]
NSSortDescriptor *sortStates = [NSSortDescriptor sortDescriptorWithKey:@"states"
ascending:NO
selector:@selector(compareCustom:)];
因此,我实现了一个"compareCustom"...然而,事实证明我无法实现自定义排序器,因为以下异常结果:
***由于未捕获的异常'NSInvalidArgumentException'而终止应用程序,原因:'不支持的NSSortDescriptor选择器:compareCustom:'
作为参考,sortDate通过以下方式实现:
request.sortDescriptors = @[sortStates]
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:context
sectionNameKeyPath:@"states"
cacheName:nil];
所以看起来我无法实现一个返回NSComparisonResult的compareCustom？我觉得它应该是可能的......但我无法弄清楚如何.如果有人可以提供一些建议我会非常感激!
另外供参考,这是我的"compareCustom"方法
-(NSComparisonResult)compareCustom:(NSString *)anotherState {
if ([(NSString *)self isEqualToString:@"Push"] && [anotherState isEqualToString:@"Canceled"]) {
return NSOrderedDescending;
}
else if ([(NSString *)self isEqualToString:@"Push"] && [anotherState isEqualToString:@"Busy"]) {
return NSOrderedDescending;
}
else if ([(NSString *)self isEqualToString:@"Push"] && [anotherState isEqualToString:@"Finished"]) {
return NSOrderedDescending;
}
else if ([(NSString *)self isEqualToString:@"Push"] && [anotherState isEqualToString:@"Push"]) {
return NSOrderedSame;
}
else if ([(NSString …我一直在寻找解决方案,我找不到一个.
假设我输入单元格A1:= if(A2> 1,1,0)
Excel将解释它并返回1或0.
但是,我想要做的是将该公式转换为字符串:'= if(A2> 1,1,0)'
如果按Ctrl +〜进入Excel,您将看到所有公式.总而言之,我想要做的就是采用所有这些公式并使它们成为字符串.
(如果您关心,目的是将这些字符串与另一个工作簿进行比较,以确保我没有删除任何内容)
我已经绞尽脑汁待了一个星期.如果有人可以提供一些方向,我将非常感激.
我已经大大简化了这些基本步骤的问题.
这是代码:
NSString * data = @"JVBERi0xLjIgDQol4uPP0w0KIA0KOSAwIG9iag0KPDwNCi9MZW5ndGggMTAgMCBSDQovRmlsdGVyIC9GbGF0ZURlY29kZSANCj4-DQpzdHJlYW0NCkiJzZDRSsMwFIafIO_we6eyZuckTZPtbtIWBi0UjYKQGxFbJmpliuLb26QM8X6CJBfJyf99ycmFF6xJagWrrMxzwJeCEMd-gFjWBC1dLPeCJFkbl_fTKfwnTqt1CK0xIZyEwFYZ2T-fwT8KnmIxUmJinNKJyUiyW7mZVEQ6I54m2K3ZzFiupvgPaee7JHFuZqyDvxuGBbZdu8D1y-7jYf-2e__C2KOJm9dxfEqqTHMRXZlR0hRJuKwZau6EJa-MOdjpYN_gprq8xVW7aRp0ZY162ySbktoWvxpPZULGxJLSr-G4UuX-QHrcl_rz_2eqvPgGPPWhqg0KZW5kc3RyZWFtDQplbmRvYmoNCjEwIDAgb2JqDQoyNDYNCmVuZG9iag0KNCAwIG9iag0KPDwNCi9UeXBlIC9QYWdlDQovUGFyZW50IDUgMCBSDQovUmVzb3VyY2VzIDw8DQovRm9udCA8PA0KL0YwIDYgMCBSIA0KL0YxIDcgMCBSIA0KPj4NCi9Qcm9jU2V0IDIgMCBSDQo-Pg0KL0NvbnRlbnRzIDkgMCBSDQo-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-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-Pg0KZW5kb2JqDQozIDAgb2JqDQo8PA0KL1BhZ2VzIDUgMCBSDQovVHlwZSAvQ2F0YWxvZw0KL0RlZmF1bHRHcmF5IDExIDAgUg0KL0RlZmF1bHRSR0IgIDEyIDAgUg0KPj4NCmVuZG9iag0KMTEgMCBvYmoNClsvQ2FsR3JheQ0KPDwNCi9XaGl0ZVBvaW50IFswLjk1MDUgMSAxLjA4OTEgXQ0KL0dhbW1hIDAuMjQ2OCANCj4-DQpdDQplbmRvYmoNCjEyIDAgb2JqDQpbL0NhbFJHQg0KPDwNCi9XaGl0ZVBvaW50IFswLjk1MDUgMSAxLjA4OTEgXQ0KL0dhbW1hIFswLjI0NjggMC4yNDY4IDAuMjQ2OCBdDQovTWF0cml4IFswLjQzNjEgMC4yMjI1IDAuMDEzOSAwLjM4NTEgMC43MTY5IDAuMDk3MSAwLjE0MzEgMC4wNjA2IDAuNzE0MSBdDQo-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-XQ0KPj4NCnN0YXJ0eHJlZg0KMjcyNg0KJSVFT0YNCg==";
NSData *decodedData = [[NSData alloc] initWithBase64EncodedString:data options:0];
NSLog(@"Decode String Value: %@", decodedData); //prints null .. and thus the problem
为了给问题更多的上下文,数据来自gmail rest api附件.附件以base64编码(MIME类型为pdf).通过获取该附件来检索上面的字符串.我能够通过字面意思正确地解析它在python中:base64.urlsafe_b64decode(data)..所以我知道字符串没有格式错误..我在iOS上做错了什么..只是无法弄清楚到底是什么.
无论如何,如果有人可以帮助我解决为什么iOS上的解码失败,你将成为我个人的英雄和救世主.
我正在实施一个UICollectionView.
在这个collectionView:cellForItemAtIndexPath:方法中,我分配了一个带有少量出口和一些自定义按钮,标签,textview的类(因此为每个自定义按钮和标签调用drawRect).
每当每个单元格出现在屏幕上时,都会调用alloc init ...导致滚动不稳定.
我的问题是,是否有更有效的实施.我明白这dequeueReusableCellWithReuseIdentifier: forIndexPath:就是原因(我认为)并且我理解它的重点但是有可能比我现在更优化一点吗？
谢谢你的帮助!