Upload a file then delete this file ,Error 412

[zhongguodaduan]

I use office365 sdk, recently i find a issues, upload a file then delete this file, it's error,but if I re-run the app to delete this file, it's ok.
I remember it work well before.
this is my code:

[[[[[[client getfiles] getById:_id asFolder] getchildren] addItem:item withCallback:^(MSSharePointItem *item, MSODataException *e) {
                                        
										__block NSString* _id = item.id;
                                        
										[[(MSODataMediaEntityFetcher *)[[[[client getfiles] getById:_id] asFile] addCustomHeaderWithName:@"If-Match" andValue:@"*"] putContent:body withCallback:^(NSInteger result, NSError *error) {
											[[[[[client getfiles] getById:_id] asFile] read:^(MSSharePointFile *file, MSODataException *error) {    
                                                    [[[[[client getfiles] getById:[path lastPathComponent]] addCustomHeaderWithName:@"If-Match" andValue:@"*"] deleteItem:^(int status, NSError *error) {
                                                    	NSLog(@"error %@",[error description]);
                                                    }] resume];
                                                    
											}] resume];
										}] resume];
									}]resume];

this is the error message:

error = Error Domain=Error in the Request Code=412 "(null)" UserInfo={error={
code = "-1, Microsoft.SharePoint.Client.ClientServiceException";
message = "\U8bf7\U6c42 ETag \U503c\U201c"{773C002E-73B3-4945-86DD-8C0E5B4FACA0},2"\U201d\U4e0e\U5bf9\U8c61\U7684 ETag \U503c\U201c"{773C002E-73B3-4945-86DD-8C0E5B4FACA0},2"\U201d\U4e0d\U5339\U914d\U3002";
}}

Anyone can help me?
Thanks.