objective c - iOS PFBatchFaultingArray - causing bad UITableView performance(?) -


i use core data nsfetchresultcontroller in 1 of apps. i'm looking ways improve performance, , 1 problem have uitableviewcontroller. it's bit jaggery. i've used instruments time profiler , found following:

enter image description here

it seem called following method:

- (cgfloat)tableview:(uitableview *)tableview heightforrowatindexpath:(nsindexpath *)indexpath {     [...]     post *cellpost = [self.fetchedresultscontroller objectatindexpath:indexpath];     [...] }

i wonder if there way solve this? or can else causing performance hiccup?

pfbatchfaultingarray kind of array executing fetch configured [fetchrequest setfetchbatchsize:20]; (or number > 0). acts regular array, it's -objectatindex: method fetch fetchbatchsize-ed group of objects disk if needed. can slow, keep memory usage low, because fetchbatchsize many objects need in memory, not [array count] many.

you try configuring fetch request batch size of 0, disable this. sure can fit objects need in memory.

optimizing app's core data performance may lot more involved 1 change, though! there's overview of techniques in core data best practices (2012 wwdc session).


Comments

Post a Comment

Popular posts from this blog

linux - xterm copying to CLIPBOARD using copy-selection causes automatic updating of CLIPBOARD upon mouse selection -

i've tried various ways coerce xterm (versions 285 , 292) copy selection clipboard clipboard whenever press ctrl-shift-c. promising way far has been, in ~/.xresources, put this: xterm*vt100.translations: #override \ ctrl shift <keypress> c: copy-selection(clipboard) \n\ ctrl shift <keypress> v: insert-selection(clipboard) ctrl-shift-v works perfectly, copying has nuance... if restart xterm, highlighting text puts things in primary clipboard; expected, proper, default behavior. if hit ctrl-shift-c, copies current selection clipboard clipboard. the bug, however, if highlight text after first time pressed ctrl-shift-c, you'll see highlighting copies both primary and clipboard. cannot figure out how stop xterm updating clipboard upon selection... , doesn't make sense me in first place. i said, @ specific point in time, copy selection clipboard... yet starts updating automatically upon selection after doing once... anyone have workaround...
Read more

c++ - qgraphicsview horizontal scrolling always has a vertical delta -

Image
i've subclassed qgraphicsview custom canvas used in cad application. i've reimplemented qgraphicsview::wheelevent check keyboard modifiers control key and, if control key pressed, zoom. i'm trying implement horizontal scroll when user holds shift , uses wheel. the problem i'm having horizontal scrolling always scrolls 0.279. not huge problem, hugely annoying , points else being wrong. so, here questions: is right way implement horizontal scrolling? if not, is? how eliminate delta of 0.279? thanks in advance. code , sample output below void myview::zoom(int delta) { double factor = pow(1.2, delta/abs(delta)); this->scale(factor, factor); } void myview::scrollhorizontal(int level) { qpointf center = maptoscene(viewport()->rect().center()); qdebug() << "center: " << center.x() << ", " << center.y(); centeron(qpointf(center.x() - level, center.y())); } void myview::wheelevent(qwheeleve...
Read more