xcode - When do we need button to send argument in Swift? -

-

when connecting button in xcode @ibaction func, can choose between arguments: sender or none.

when choose sender , when none?

well, if action method needs know button triggered it, or can make use of of button's properties, need pass sender (the button) method.

a contrived example if have calculator, has '+' , '-' button. both share action method performcalculation(sender: nsbutton) , method use sender's symbol (this button's title) perform correct calculation.

on other hand, if have button, example clear input on textfield, wire button method clearinput() not need have information button triggered (in fact, having no argument here make easier reuse method elsewhere in code , trigger clearing textfield programmatically).

i hope makes sense you. there no clear rules afaik. it's matter of taste guess.


Comments

Post a Comment

Popular posts from this blog

java - Could not locate OpenAL library -

-
i writing game using slick2d library, uses lwjgl. lwjgl version 2.9.3. using netbeans 8. i tried adding sounds game, example music track on main menu. problem is, exception when run game, despite game still compiling , running except sound of course: sat mar 21 01:23:57 edt 2015 error:could not locate openal library. org.lwjgl.lwjglexception: not locate openal library. @ org.lwjgl.openal.al.create(al.java:156) @ org.lwjgl.openal.al.create(al.java:156) @ org.lwjgl.openal.al.create(al.java:102) @ org.lwjgl.openal.al.create(al.java:206) @ org.newdawn.slick.openal.soundstore$1.run(soundstore.java:295) @ java.security.accesscontroller.doprivileged(native method) @ org.newdawn.slick.openal.soundstore.init(soundstore.java:292) @ org.newdawn.slick.music.<init>(music.java:156) @ org.newdawn.slick.music.<init>(music.java:75) @ view.mainmenu.init(mainmenu.java:58) i didn't include rest of error states error happens in game code. the...
Read more

c++ - Delete matches in OpenCV (Keypoints and descriptors) -

-
i want check scene image against 2 train images. that, detect features , compute descriptors of both training images. before detecting, computing , matching scene image, delete matches of train1 , train2. because these matches won't facilitate matching of scene image train1 , train2. so, match train1 train2 , vector of matches trainidx , queryidx. how can delete these matches in keypoints-vector , descriptor matrix of train1 , train2? best regards, dwi i have done below: std::vector<cv::keypoint> keypoints[2]; cv::mat descriptor[2]; std::vector< cv::dmatch > matches; /* write code generate keypoints, descriptors , matches here... keypoint[0] -> train image 1 keypoints keypoint[1] -> train image 2 keypoints descriptor[0] -> train image 1 descriptors descriptor[1] -> train image 2 descriptors matches -> matched between train image 1 , 2 */ // logic keep unmatched keypoints , corresponding descriptor...
Read more

sorting - opencl Bitonic sort with 64 bits keys -

-
i used nvidia sdk bitonic sort , works great me. 32 bits (uint) need ulong keys. have typically 2^14 keys @ time , power of 2. searched on not find kernel designed ulong. i tried modified nvidia sdk bitonic sort using ulong keys not work. kernel not crash after de call clenqueuendrangekernel got error : cl_invalid_command_queue can tell me how modify bitonic sort or radixsort, or can sort ulong keys? i running nvidia quadro 4000 opencl 1.1 cuda 6.5.20 full_profile used original nvidia sdk bitonicsort.cl i used"ulong" keys , value input , ouput instead of "uint" thanks helping i made work-around suit need. used 30 bits of key , 18 high bits of value sorting. changed comparators (2 lines): '#define mask 0xffffc000 // suit need from this: if( (*keya > *keyb) == dir ) this: if(((*keya > *keyb)||((*keya == *keyb)&&((*vala & mask)> (*valb & mask)))) == dir ) it works fine. but, still, it's work-a...
Read more