NSData转化为图片
NSString *string = @"http://img0.bdstatic.com/img/image/shouye/mxfbb-9427886853.jpg";
NSURL *url = [NSURL URLWithString:[string stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *Image1 = [UIImage imageWithData:data];