-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage *newImage = [info valueForKey:UIImagePickerControllerEditedImage];
    if(!newImage)
        newImage = [info valueForKey:UIImagePickerControllerOriginalImage];
    inserImage = newImage;
    CGFloat width = inserImage.size.width;
    CGFloat height  = inserImage.size.height;
    NSLog(@"inserImage.size.width:%f    inserImage.size.height:%f",inserImage.size.width,inserImage.size.height);
    
    //定义缩略图的大小 #define IMAGE_W  72 #define IMAGE_H  98
    
    
    CGFloat lValue = width/height;
    //300/250
    if (lValue > 1.4f) {
        if (width > 280.0f) {
            width = 280;
            height = roundf(width/lValue);
        }
    }
    else {
        if (height > 200) {
            height = 200;
            width = roundf(height*lValue);
        }
    }
    
    
//    NSData *imageDatas = UIImagePNGRepresentation(inserImage);
//         NSLog(@"imageDatas:%@",[imageDatas description]);
//    NSString *aString = [[NSString alloc] initWithData:imageDatas encoding:NSUTF8StringEncoding];
//     NSLog(@"aString:%@",aString);
//    NSString *base64 = [[aString dataUsingEncoding:NSUTF8StringEncoding] base64Encoded];
    
    
    
    NSData *imagedata=[NSData dataWithData:UIImagePNGRepresentation(inserImage)];
    NSString *base64string=[imagedata base64Encoding];
    NSString *uuids = [self getUuid];
    [[BCAppDelegate sharedInstance].USERINFO setSaveAvataPath:uuids];
    [self saveImage:inserImage imane:uuids];
    if (_delegate && [_delegate respondsToSelector:@selector(myInformationUpdate)]) {
        [_delegate myInformationUpdate];
    }
    [self uploadAvatar:base64string];
    [self dismissModalViewControllerAnimated:YES];
    
}```

NSString *base64string=[imagedata base64Encoding];

 把NSData 类型直接转换成base64 字符串上传 头像一般这么做