解决方法
这应该工作：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *docs = [paths objectAtIndex:0];
NSString* path = [docs stringByAppendingFormat:@"/image1.jpg"];
NSData* imageData = [NSData dataWithData:UIImageJPEGRepresentation(imageView.image,.8)];
NSError *writeError = nil;
if(![imageData writeToFile:path options:NSDataWritingAtomic error:&writeError]) {
NSLog(@"%@: Error saving image: %@",[self class],[writeError localizedDescription]);
}
