iOS 写入2倍和3倍图片到沙盒

/**< 写入2倍和3倍图片到沙盒 */
- (NSString *)configTabbarItemImageWithUrl:(NSString *)imageUrl {
    NSArray *stringArray = [imageUrl componentsSeparatedByString:@"/"];
    NSString *imageName = stringArray.lastObject;
    NSArray *tempArray = [imageName componentsSeparatedByString:@"."];
    NSString *newImageName = tempArray.firstObject;
    NSString *doubleImageName = nil;
    NSString *tripleImageName = nil;
    if ([newImageName haveValueString]) {
        doubleImageName = [NSString stringWithFormat:@"%@@2x.png",newImageName];
        tripleImageName = [NSString stringWithFormat:@"%@@3x.png",newImageName];
    }
    UIImage *loadImage = [UIImage sd_imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:imageUrl]]];
    NSArray *pathArray = (NSArray *)NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask,YES);
    NSString *path = pathArray.firstObject;
    NSString *doublefilePath = [path stringByAppendingPathComponent:doubleImageName];
    NSString *triplefilePath = [path stringByAppendingPathComponent:tripleImageName];
    if ([UIImagePNGRepresentation(loadImage) writeToFile:doublefilePath atomically:YES]) {
        XLog(@"写入2倍图片成功")
    }
    if ([UIImagePNGRepresentation(loadImage) writeToFile:triplefilePath atomically:YES]) {
        XLog(@"写入3倍图片成功")
    }
    return [NSString stringWithFormat:@"%@/%@.png",path,newImageName];
}