Nsfilemanager gets stuck when initializing a file.

Debug a program today. The content is to generate a cache file in a local path on the mobile phone. When the local path is generated, an error is made. In the spirit of seeking for reasons, debug the program for two hours, I finally found the reason.

At the beginning of breakpoint debugging, execute row 13th. No data is written here, and no is always returned. As a result, I am all broken, and then the printed path is under the library, I wonder if it's not here

Allow the user to create a data cache here, and change the nsdocumentationdirectory of two rows to nsdocumentdirectory, and then the path is changed:

File: // var/mobile/applications/79d7dd73-74c5-4ece-bef7-5988560a8ac2/documents/436783070; then the path here can write data ..

 

Before modification:

1-(nsurl *) uniquedocumenturl {2 nsarray * documentdictiories = [[nsfilemanager defaultmanager] urlsfordirectory: nsdocumentationdirectory indomains: nsuserdomainmask]; // note nsdocumentationdirectory 3 nsstring * unique = [nsstring stringwithformat: @ "%. 0f ", floor ([nsdate timeintervalsincereferencedate])]; 4 ID urlobject = [documentdictiories firstobject]; 5 return [urlobject urlbyappendingpathcomponen T: Unique]; 6} 7 8-(nsurl *) imageurl {9 If (! _ Imageurl & self. image) {10 nsurl * url = [self uniquedocumenturl]; 11 if (URL) {12 nsdata * imagedata = uiimagejpegrepresentation (self. image, 1.0); 13 if ([imagedata writetourl: URL atomically: Yes]) {// Question 14 _ imageurl = URL; 15} 16} 17} 18 return _ imageurl; 19} 20 21 // print 22 printing description of URL on the console: 23 file: // var/mobile/applications/16614ff0-b641-4938-8bf8-91658759d4d8/library/documentation/436783128

After modification:

 1 - (NSURL *)uniqueDocumentURL 2 { 3     NSArray *documentDirectories = [[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]; 4     NSString *unique = [NSString stringWithFormat:@"%.0f", floor([NSDate timeIntervalSinceReferenceDate])]; 5     return [[documentDirectories firstObject] URLByAppendingPathComponent:unique]; 6 } 7  8 - (void)setImage:(UIImage *)image 9 {10     self.imageView.image = image;11 12     // when image is changed, we must delete files we‘ve created (if any)13     [[NSFileManager defaultManager] removeItemAtURL:_imageURL error:NULL];14     [[NSFileManager defaultManager] removeItemAtURL:_thumbnailURL error:NULL];15     self.imageURL = nil;16     self.thumbnailURL = nil;17 }18 19 20 Printing description of url:21 file:///var/mobile/Applications/79D7DD73-74C5-4ECE-BEF7-5988560A8AC2/Documents/436783070

 

Nsfilemanager gets stuck when initializing a file.