获取图片

+ (UIImage *) getImageFromURL:(NSString *)fileURL {
    NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileURL]];
    UIImage *result = [UIImage imageWithData:data scale:[[UIScreen mainScreen] scale]];
    
    return result;
}

+ (void) saveImage:(UIImage *)image withFileName:(NSString *)imageName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    if ([[extension lowercaseString] isEqualToString:@"png"]) {
        [UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"png"]] options:NSAtomicWrite error:nil];
    } else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"]) {
        [UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"jpg"]] options:NSAtomicWrite error:nil];
    } else {
        NSLog(@"文件后缀不认识");
    }
}

+ (UIImage *) loadImage:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    NSData *data = [NSData dataWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.%@", directoryPath, fileName, extension]];
    UIImage *result = [UIImage imageWithData:data scale:[[UIScreen mainScreen] scale]];

    return result;
}