To check iOS4.0 or not

#import <MobileCoreServices/UTCoreTypes.h>
 
#define SOURCETYPE UIImagePickerControllerSourceTypeCamera
 
-(void)saveImageInBackGround{
	Class aMsgClass = NSClassFromString(@"MFMessageComposeViewController");
 
	// following will check 
	// if user has device higher then equal to 3GS 
	// and using iPhone os higher then iOS 4.0 (multitasking)
 
	if(aMsgClass && [UIImagePickerController isSourceTypeAvailable:SOURCETYPE]){
 
		NSArray *mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:SOURCETYPE];
		bool isA3GS = [mediaTypes containsObject:kUTTypeMovie];
 
		if(isA3GS){
//			NSLog(@"yep 3gs and more");
			UIImageWriteToSavedPhotosAlbum(self.imgBig, nil, nil, nil);
		} else {
//			NSLog(@"nop ! Sorry compressed image will be saved.");
			// if it's not a 3GS or higher device.
			// first compress image
			UIImage *img=[UIImage imageWithData:UIImageJPEGRepresentation(self.smallImage, 0.59)];
			// then save it to photo album.
			UIImageWriteToSavedPhotosAlbum(img, nil, nil, nil);
			// this statement will take time to execute.
		}
	} else {
//		NSLog(@"nop ! Sorry compressed image will be saved.");
		// first compress image
		UIImage *img=[UIImage imageWithData:UIImageJPEGRepresentation(self.smallImage, 0.59)];
		// then save it to photo album.
		UIImageWriteToSavedPhotosAlbum(img, nil, nil, nil);
		// this statement will take time to execute.
	}
}