UIImage *image1 = [UIImage imageNamed:@"about_app"];
UIImage *image2 = [UIImage imageNamed:@"alter"];
NSArray *array = @[image1,image2];
NSMutableURLRequest *request = [[AFNetWorkSingleton shareInstance] multipartFormRequestWithMethod:@"POST" path:@"Mindex/getimg" parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData>formData){
int i = 0;
for(UIImage *eachImage in array)
{
    NSData *imageData = UIImageJPEGRepresentation(eachImage,0.5);
    [formData appendPartWithFileData:imageData name:[NSString stringWithFormat:@"file%d",i ] fileName:[NSString stringWithFormat:@"file%d.jpg",i ] mimeType:@"image/jpeg"];
    i++;
}
}];

试试这个。