remove Cache from files failed - ios

Question

I am trying to release cache from files by calling this method :
-(void)removeCacheFromFiles
{
NSFileManager *filemgr;
filemgr = [NSFileManager defaultManager];
NSError *error=nil;
if ([filemgr removeItemAtPath: [NSHomeDirectory() stringByAppendingString:#"/Library/Caches"] error: &error] == YES)
NSLog (#"Remove successful");
else
NSLog (#"Remove failed");
NSLog(#"error %#",error);
[filemgr createDirectoryAtPath: [NSHomeDirectory() stringByAppendingString:#"/Library/Caches"] withIntermediateDirectories:NO attributes:nil error:nil];
}
But I get "Remove failed" every time.
I tried this as well and get the same result:
-(void)removeCacheFromFiles
{
NSFileManager *filemgr;
filemgr = [NSFileManager defaultManager];
NSArray *cachePathList = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cachePath = [cachePathList objectAtIndex:0];
NSError *error=nil;
if ([filemgr removeItemAtPath:cachePath error: &error] == YES)
NSLog (#"Remove successful");
else
NSLog (#"Remove failed");
NSLog(#"error %#");
[filemgr createDirectoryAtPath: [NSHomeDirectory() stringByAppendingString:#"/Library/Caches"] withIntermediateDirectories:NO attributes:nil error:nil];
}
Also where should this remove caching be down ? Is it a good practise to call it in ViewDidDisappear or in ViewDidAppear so that the cache is cleared when the view controller is called the second time ?
The error in the NSLog says :
error Error Domain=NSCocoaErrorDomain Code=513 "“Caches” couldn’t be removed because you don’t have permission to access it." UserInfo={NSUnderlyingError=0x15fac9a0 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}, NSFilePath=/var/mobile/Containers/Data/Application/1795C59B-185F-4607-8682-004CDF3CDED7/Library/Caches, NSUserStringVariant=(
Remove
)}