1： 

   NSData *imageData = [[NSDataalloc] initWithBase64EncodedString:dict1[@"msg"]options:NSDataBase64DecodingIgnoreUnknownCharacters];

        _fenxiangtupianimageview = [UIImageimageWithData:imageData];

2：       

  NSData * yanzhengmadata = [NSDatadataWithContentsOfURL:[NSURLURLWithString:pinjieyanzhengmatupianlianjie]];

  self.yanzhengmatupianimage.image = [[UIImagealloc]initWithData:yanzhengmadata];