How can i show my phote on the UIAxes during the callback function runing within APP designer?

I want to design an app,when i enter the button'开始'in the left window,the button callback function works,like the right window showing .

there is four times for-loop in the callback function.what do i need is that one loop finished then a corresponding picture showing in the UIAxes on the left window ,but the fact is that only one dispaly in the left window until all for-loop finished.

the code as follow:

for ii = 1:trial_num

target_seq = randperm(target_number);%打乱目标顺序

textureGUI_tar = textureGUI_target(target_seq(1));%每次trial的目标图片

notarget_seq = randperm(nontarget_number);%打乱非目标序列

%每次trial的非目标图片

Screen('DrawLine',w,[255,255,255], xcenter-35,ycenter,xcenter+35,ycenter,2);

Screen('DrawLine',w,[255,255,255], xcenter,ycenter-35,xcenter,ycenter+35,2);

Screen('Flip', w);

WaitSecs(0.5);

Screen('TextSize',w,80);

Screen('TextFont',w,'Courier');

DrawFormattedText(w,'3','center','center',white);

Screen('Flip',w);

WaitSecs(0.5);

DrawFormattedText(w,'2','center','center',white);

Screen('Flip',w);

WaitSecs(0.5);

DrawFormattedText(w,'1','center','center',white );

Screen('Flip',w);

flushinput(tcpipClient);%清除缓存数据

WaitSecs(0.5);

imshow(strcat(target_info(ii).folder, '\', target_info(ii).name),'Parent',app.UIAxes);

end

Could you give me some adives if you meet the same question and solve it successfully? thank you here.