1.项目中实现的代码如下：
NSArray *paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path=[paths objectAtIndex:0];
NSString *dest=[path stringByAppendingPathComponent:@" "];
NSLog(@"%@",tmpContent);
[self loadHTMLString:tmpContent baseURL:[NSURL fileURLWithPath:dest]];
若用 stringByAppendingString 则需要手动在名称前加 “/”符号，而stringByAppendingPathComponent则不需要，它会自动添加
stringByAppendingPathComponent和stringByAppendingString的区别：
NSString *imagePath = [skinPath stringByAppendingString:[NSString stringWithFormat:@"/%@",imageName]];
//stringByAppendingString是在skinPath加后缀的意思
NSString *imagePath = [skinPath stringByAppendingPathComponent:imageName];
//stringByAppendingPathComponent是在skinPath后面加上“／”号连接imageName让它成为完整的路径
NSLog(@"imagePath:%@",imagePath);
打印：
imagePath:/Users/will/Library/Application Support/iPhone Simulator/7.0.3/Applications/DA5B603D-4D07-4425-B7CC-5D49232189BE/Willing.app/tabbar_home.png
