.plist writing error on device

This snippet of code does work on the iPhone simulator but not on device, although I am looking for a file that has been written on disk in the documents directory

NS开发者_运维问答String *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *filepath = [documentsDirectory stringByAppendingString:@"notificationScheduled.plist"];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:filepath];
if (fileExists) {
    NSMutableArray *array = [NSMutableArray arrayWithContentsOfFile:filepath];
    NSLog(@"%@", array);
    [array addObject:date];
    [array writeToFile:filepath atomically:YES];
} else {
    NSMutableArray *array = [NSMutableArray arrayWithObject:date];
    [array writeToFile:filepath atomically:YES];
}

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Yes. To save a property list: this may help u

if not just leave this ,since it may help others

NSString * error;
NSData * data = [NSPropertyListSerialization dataFromPropertyList:yourPlist format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];
[data writeToFile:pathToYourFile atomically:YES];

yourPlist must be a kind of NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary object.

To read your property list.

NSString * error;
NSData * data = [NSData dataWithContentsOfFile:pathToYourFile];
yourPlist = [NSPropertyListSerialization propertyListFromData:data mutabilityOption:NSPropertyListImmutable format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];

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Found the answer, instead of

NSString *filepath = [documentsDirectory stringByAppendingString:@"notificationScheduled.plist"];

Used

NSString *filepath = [documentsDirectory stringByAppendingPathComponent:@"notificationScheduled.plist"];