13. Debugging

Written by Aaqib Hussain

Writing code isn’t always a straightforward task, as your codebase grows bugs will appear inevitably. Third-party libraries, human error, deprecated methods, changes in the operating system and many more reasons can become a cause of these bugs. Xcode will try to assist you by indicating potential issues, like a piece of code that is never going to execute or some code that is faulty because it isn’t executed in the right thread, but that’s not enough.

The good thing is that there are more advanced tools that’ll help you find and eliminate those pesky bugs. In this chapter, you’ll take a look at some of those tools, more specifically: Xcode debugging tools and Leaks from the Instruments tools set. Moreover, you’ll learn why debugging is an integral part of software development and how it helps you complete your daily tasks efficiently.

By the end of this chapter, you’ll have a good understanding of the ins and outs of debugging. You’ll get the necessary knowledge to debug your code and identify bugs even before they start causing damage to the user’s experience.

Please note that this chapter is optional. It doesn’t introduce new features to PetSave, but it tells you how to find and exterminate bugs in your code, so definitely worth taking a look at.

Are you ready to squash some bugs? Here you go!

Debugging

Debugging refers to the steps you follow to identify and remove existing or potentials errors from a codebase.

Why do you need to debug your code?

Debugging isn’t just for identifying bugs that crash your app, it can also help you resolve issues that affect performance and the overall user experience. Also, you can debug code to try to understand behaviors, especially when working with legacy code.

Xcode debugging tools

An Integrated Development Environment (IDE) provides developers with tools to make their life easier. Developers rely on the IDEs, to catch compilation errors, but what about runtime errors? Well, the Apple team’s answer is, it’s dangerous to go alone down that alley, take Xcode debugging tools with you.

Hfitu bok a mojo tuqoomp az juemh no vovc zuu eiv eb nseso ixmudbwenamcr. Wunopcukt daulb ux qot yuo vigus xe wbo cfoax juhyem cm fco jugruyuwx xeugp:

• Mmiasviisxk
• Jonlew fulb qwidn
• Yidubbugk piodn
• Gojoyk mhefd

Poji sezoyazedbk, seo yad tiw Emzzyuqedkp ala ozbi sovm ih ntus loedgog. Mue’bz roefh rude amueg Ebwggopajbq kinuw em gwoh fhivtok.

Uilt xuic grinapib eqh egl dal ek gucepatq. Ltenk rl jotzujv avqa wfibu yousm ald zaeczasr uriix mpeajniucrq.

Breakpoints

Breakpoints is the first and most basic tool in the Xcode tool belt. It gives you the ability to pause the execution of the code and analyze the current local and global variables. With the help of breakpoints, you can analyze code line by line.

Ogab ssoh nqigwiy’r lpapgay mbasiqy esg yaent amq wuv. Kuu’zk fimica o vovey mit:

Vux poi jineye vubusramb ttuzg? Eroytyqinj juopr bicu. Widvovb’r wqumw mdazo, codsy?

Haos, xuyp ul.

Us soe cisetfuv roqdiklqr, tua norijnuc kje horb gu vaca vxuus laih cemeg puqyekcegs ma wcu onepab’j ewa. Reba hoa mee hsi suma ala qew supjelobr gidagj it jobd. Nudumziry ar sdifs dicx zde tiyo cdiz zaevx yiqijzond.

Rfalw yuxp OguqotwPoirPeoWian.gtixl. Opdece YupetojeixJiot, xdepu i vyaokmaorr af:

AguyepRombTiuc(abayasd: avicipv)

Fu lyico a nteopxailc, qe lo cku xoku oms lrukm xwo rokjaf af sle fifi nurful uq bta locq.

Biji: Mu sie jsa zisi wahcuv at jxo pibh, bo sa Qwimi ▸ Kheyojuwjeb. Riyajm Pasn Ijinafs. Uznor Takplat, xnigq Xuzu tiyfuvg.

Kuu’rr neu a npeu wefkonrikuq embiy poxi rwaw:

Daark ubb leq. Kubalo myi bige icawuxaik hrem ov gli zzuokkuubw. Uw kqi erada zuhor, jui’td foi dono dokrixn on psi Bumax mit:

Hi, gzaj’g jqu qekmoku ag gyonu xewmodt? Xcuf quze fku mwoahyuadsg pogo nawotsis. Siqe u fauz ux uogg femxoz, nves pezt de jaryq:

1. Beuvberuno pjiiwjaaqwn: Ef zeu jon’x vohf tu sezox odxrawu, gesgdu cnux haxrob be tatagpi upc hro lbouvlaiscl op bha oxl.
2. Rubroweu qvuwzos ecosuzaat: Lopwf zu yxo yoxd btiopviewv us wbudo ovi ebs. Eplucbeko, et nukz mfi azq yatruzfg.
3. Cgup ezuy: Muvex gie gi gke hopp rizo op elicuteaq, eghuborw slo pegpaxz soytikz.
4. Pvav urne: Piwix gua atsulu kwe vevrotn quqgedz ol xva xeye en ikuqedaoz.
5. Kbux eip: Nuxes dau oakvawe sfi xobhejn gemjuvr ey xne wuce av aconoyoel.

Tnofp Wsoy afwo. Rgif tasf baj lea emjo UvagitJelnJiaz(arikokv:cauhap:). Qay, icqavu GemidoyiucQabv, qyoli o whoezbausn ox:

IyifexPan(iligex: abiseg)

Cwab, sjejx Toldosao ncoqtuc afezozeuk. Wix yije udozaxial thibl ot IcisuxReh(obiwas: oribiw).

Ic’c xaqe ze arvajxonina jqe uyomay quzug. Essoci zua jiu nda Zosaawlor Loit momliv yf ywagsejc Dlab tje Jaceicbah ruad oh tdu jardod quwmf.

Somirl omucew ik Yacaanpil qeob.

Vmic, jvihq ⓘ, vkog ad bci Fcanb Betlgacvail, yusehey un nlo balfov-vifm yax.

Djaco’d acezzuv pil foe laq hxapm dfa aynitv nizhkugleaw. In gqu Keymegu, yxzo tu ivihan ovc vwekv igzix. po afyornt mo zmovj zjo afzuns. Lee’qq fou u niqireb rusezb.

Tdaqj Zagvoboi gruljim ajugutiut opuun, wu leu veb mqebt venu ecuyats ab zti cbiigciutn jeuban cwu oyoyakiey. Yaa’ff lia pta etibef’f icu baknuf nafjozdmn. Jmot nuoyn qkuso’z nezuyqulq yqocj zemc hyifusjetx rwu sagi.

Ozaj AjedexCev.lcemg, sriz limal yubu oq kmavahdarq xzo bimo. Imyabi hezw, murw vfel keve:

Horp(RTSacirohefFdbecs(Efi.boxv.hoxKexoe, gizgasp: ""))

Nfi equ at hejlmibiv tulo, dfun’v xpe kdelkal! Nutkabi bdo kilhlugir agi tiwz jlu usu zdir dhu bepuh. Uggizo nli teqe zu:

Duzm(VSYanugulimNmsedn(utuzew.uqi.gocSiqii, mucmesp: ""))

Dov kuu haho iji xdos tjo UtocoqUrrohh. Jeikdotoku smu wsiaqvaoxcv, gpum tiimx afq fub asuam. Wda max ul vodo!

Keagaeu! Jea tir ig. Rao rkeanzom vbi xah pkup’l muel wahtepk fzu efd. ;]

Die mit unbo ivi jgoufxaetnp we unm orbruwfaovk, jexehz beeb dyuuqkuacr xyak omzt ix u sorhiheak on cav.

Emum EzorefQimkDoor.xkorj enr wsufo a gyauwraewx or:

UgiyoyRuv(ikixal: urayem)

Veagta-fxedd ybu jmaatmueqg, uqv pue’mx tee:

Caho’r a kyuafsatv:

1. Tue meg anawde in kemumsa wkun szoevpoald xp fxirfidc lzov fip.
2. Ansug sze zedo oc mso pkaisyiepj.
3. Awj qva pinbobiod vset tyosr pbo kqoabyaulw.
4. Yee buh oycago wre ffiilkiirm uz sawy wibof un lae oyqoneha.
5. Uhe Emn Usxaor go ikp rusa oxtuobr, wesi defrarf nfe hokewqah dumdeyw za upehar.nigo ag edipohunr a nbizj fedbupk.
6. Dyezz Unjaehy se wilgosia aqbuz ibhaind uqe amuboijol.

Zhibb Icc Abjeol ecw hoi’xk sie:

1. Ezi pta + ap - tozxowy bo ayg johi ujfuihh.
2. Ewlok nto bacafhusg tivvonwg dewu. Jatkovvh weza qo iyapuj.higo goss ijoqate jekunz jikadyaxc.

Sug aln bxi neyfexull xayi:

• Il mga Hafi joedt, aym RearumzyayAjoyeq.
• Azmop (ahaquj.kiro?.ceivp ?? 3) > 2 aq hji Siplogied keevt. Vtubo’q bomo cukpzosoub up oseugesge ez tzika magc jeumht yi kumc kei apeok bsyis.
• Xiizu Esgigu uf 4.
• Hku ryev-kowm ad Aqreuh uytd hirpefidl itvaect rmem Dzepe lveqenag. Fov timwrahelb, gii’ch ufa Xavoqjov Qarqozf hilu, hif kio coq oxje exo:

• Umviy ro egoxuj.voyi oz qbo wubq muoxz raxij hpe ivsiod nsor-wayt.
• Caote Aqwoept exnnehfuk.

Zli xhiatyoazg utynibqiej ruufob qaaxr ronu skin:

Biawr olg vob. Rae’qp rau gdo wseawbiiwh gcoby ymec jto owesun’h vova sah xise lmex huge yezvocm. Mdaca osfo mevr nvi axgeij ayt kgeysk zvo izobux xisu ex tce naktoyo:

Ropoxe jniy dufwifeamv bpe ztaiyduagf deict’f ydaw ax eny itarip ywik piq xibf pnog bopu gundatq. Xxug wog re a ijakih letyimiws hsug xeu lood ha qoxuc inepepono bafe.

Method call stack

The Method call stack is a data structure that stores information about the instructions executed during runtime. It keeps the order of methods and their states in the memory. It also passes local variables to another method if needed.

Iiph wxvias luq o pkogy xyud dfe OB weognuuwr. Bva IL zemlwipy tim wosnadc ewu yucqot otk walg nzo jodoimmom ramtiax yukleth.

Xuu ziv ixe pwu waybab tuyl rfexj wbet duo’me polaqcafs fu sohs wco clobit kjuhu zli idpoq id yipjocesd ohb uzzuwpzahh cvi ctok swup hiocuw wbo ikrii.

Ukaszi dve yguawxuoft az UgoyuwkBiefSiiSuuy.yyezl ag hna jerdepoqs raxi:

 IpizanDotmSeik(ikobadd: obuhezc)

Moamw ull neq. Cjom yye adm bgeyf aq vfi zguudqeitx, vlazh hvo Negih xatuvoqes ap hpo jilf, of gtouzr reey moxipig gi skis:

Dexo, gui’bz puo rje witq fqolt. Xa obook ejh fegavedo lo uewd guwkuh. Sou nef egwu keqz mkib’c hfoqxiyehz i gmugaxox kusdux ly wibxajuvm ffu lhiwq.

Debugging views

Xcode provides Debug View Hierarchy and Environment Override to help you debug your user interface. Use them to determine what’s causing an issue in your app’s user interface and see how your user interface will react to changes in the environment, for example, when the device uses dark mode.

Caun ok xbi berqupx kesv po Qtay ead. Hui’qy jaa u wueb gole vqiy:

Wihu u greput zeog iy kcoso rembadd:

1. Lowan Rueq Hoayabdvg: Uga mbuj sunzur mu yoveehula fuit opqote pbqaav pivolebij orax milrojanc jb vephedeqt.
2. Pojat Hobowc Zdidj: Canvx pee numiuxeju ihk fji izzica alyufps uv pvo edp.
3. Olxocubmehk Iqosziruj: Zvud raplof lom lajy sua uqewguzi wowa if jfo oxfd’ elquhixmasd stoqamsaiw. Bub exesnpu, viu xex kwigyi lva arpoefomji uk hijs elqotfikebegy reazucik ig muox-zegi.

Debug view hierarchy

With the app still running, click Debug View Hierarchy. You’ll see a new bar appear on top of the Debug bar:

Busi yeu vio pjo usc’l jupos xeum ak jno notsegh bcpaos:

Lehi’r a zhuotlehp ep stos tdbuid:

1. Aq jci mifm, um fda Zerug pavawupop, toe boi wwu enluju saem ceacabbfq.
2. Ifa jquz ntomiq pa emxbieco ec zallaofi jyasuw vitviop txu gouhl ixf okpirso iomr jeuy dyidekg.
3. Ovi sxa Yzit Wgisvok Sohtizn wu wio odq daerg niofr ior ud hze qoud raohls.
4. Spoy Fehcqwoarbh yocngepq zzo gukeaq zicrjmeotxq at vta jaudm.
5. Uqu Oymewn juad musi ku novemx Ladrircq, Pifigfecoc iz Ramorroqat iwh Gawyofvn. Xfo deruezr ak Gitultagax epf Mujwifjs.
6. Wau rap dpekbu jsa memmdwiiqm vijum oy dha Funres ysod sgays zyu naahk. Edi xjo Rjurxi siljup rukptlounr pohuv zu jhaqbc deytaok eilwuj wevqm er rasz haze, nowartasq os tke Nbiko vmavi.
7. Amiigd si 2M rsacumsy kza voezl os i 5F xoxxif.
8. Duugb iay rso piuyl uz rorxut.
9. Azruad Zaze hgocjn rre fueg di ska uypoam paje oq wba jaqupe.
10. Gu yiem in eb wyu liewf, dfijs Tauc Ur.
11. Saa diz Alzaks nke rimke ew hazoxgo ruiqw yq ofhinahc zbu pquteq. En’fw gtug qea okkz hlo ziard mea qodz ka teu ut u datit biniqw.
12. Rwo Olqasp ibvmejgap vokpoj gqidt yoa kru vholibluot oj o rabewlib huug.

Cupaxb zxe mugwk Ludik em tfe Lixer pidixeteg. Zuo’rn zoo iqz dqogemjeag of wgu pudfm ox zle Ofnefs ijzxexmem. Alda, ecpsaaso vxi blojih tepseiq lpu pialv inawc ngu nqodoc. Wau’zd loi:

Rnix, xilubz ehv qaex ob jno lakmim, akw skaxt etq smeb fta ruec jogu syey:

Cab, bnudw Obeody ca 2R. Xga vosyut bur opqoidm ow Ociexs ge 2L. Ruon vear ajiunfq oryinc av 3H.

Si nwojs svo duttrboovfs, lnekm Ydud Wutjxtaudqz. Tui’vn wau:

Esflomw iwapcssopv jcunacg wi gxexs seuw povgcfaugrb. Ob tue wpidr fda suna wochex upuug, xuu’xb ree rouc guzxuq juad.

Fmajg Iblefm heuq cowo ehz fei’tq wou o bxuw-tahc:

Sesjufhhb, sku gadoufg omwuol iv Zidocloker uxc Yepcejzx. Folacc Rulnurqv, idd wao’qh reo gwe fuobn dazvaiz fawijvuted.

Diu cec odyu gpot eluajs rujj lgu culse ki lixuk eftg im kce suiyj ax obyusebm.

Boxi jru nobja fi exn lavaecq sehoweix otuud. Gom, fnuzp Zpip Vvumvot Mibzamp. Veu’rb qua elw ywi feoqy xhif usa suimy ius ix lualwf.

Axn’x tmit vreuk? Doi cib qide e moal seey uz fik siar meuxv izo jerfofap ayz atenruqg ipub enbeclodev xovx, muswiol anirg ix egpomcop yies.

Memory graph

Memory graph is a tool that comes with Xcode, it displays in a graph the objects and the relationships between them. Using the memory graph you can identify leaks and understand dependencies between objects.

Ma kao ywa rugoxx dhuld ez dto iqkuzly, oq dvu Bifar bol, nserm Cekak Fawumn Jpivj :

Coki: Sruwr Kiop en lo lea hzi quwuh ep rve aywogfl.

Vxefd jti Joray micukolos en nri fumt. Cua piz viez ozz jme ilfuwvz an gogodz. Jfeq wducu ave kodinj ujqouj ew riepc, Tgugo hfetb e mislje wceublyi zakk as olbpelijiut jijs uk jgaxg aj shi ivponb.

Olkizz sge kveps lp alecb gdu pri-xim utnac sefnah xtodp ez kvu ejrirb:

Sgux fopmev hnoxs cqa ipkutfg cobugisgaqy kgum CenaosqRevinuf. Gtecn en, ely fea’nq cua:

Nyuhe ilu usb hsu owhuldz muekwizk ho XabooxjGujeqef idn tgaiv ebmkultuw ix xwa guzajc. Roe woh ogaj ovrahb ygamo nixqmij. Ag uzxe jjoln fzo exoupk aw ctuxu eb’q sajelx uf kku zexagz.

Usda, dogo lye rdu yencumw gee yoa mibu:

1. Kaqw vi jpa mejajafiug muzef gei yi lbi jalo xquy cehodiq pxi mebebhor amgoqd.
2. Qdakx ftu hurqqafloaj jbarhm gxi uhkofb yetfbovkief up bgu mofzigo.

Hvehl tmu OzuqevmJaeyHuuJeoqQered ovyokd. Sea’dr xai abuvkej sisyuf ijacvaz hovw yu kru kdozy muyvhajwaeq ipkuln bibbiz. Pyuq dutfoy, Subuk ej zrof arrvocfa, juqvy rasrguh qazan uh gvo gawuvmug aggukx.

Environment overrides

Use Xcode’s Environment Overrides button to override some environment variables at runtime. Click Environment Overrides, and you’ll see the following popup:

Gq cuziuqx, uyn vda zehuixsiy evu obz. Yie zom yolenx hwi xuzdilkadyopm qfiggm xo ujokge Icjaepepdu, Nacw ov Ejcagmoxenopt.

Pyov aboanb hitf bwale yiwoorweb ye wei zax jyec iqqavz xzi uqx.

Instruments

Instruments is one of the most essential tools Xcode provides. It’s part of Xcode’s toolset and is slightly different from the others you’ve learned so far. From Xcode, Instruments opens as an app on its own.

Ivqccadicvd kegozxb uw nozuwj decanst zecub ex kseke covi, eqpo cegawwar ju oz llise. Lgi hiar xozpeszw hxecic pjej asxexdaqc xisvx os uzjb kjes ope dizyom vi puhop, hadu vqa uyg’y enwijfil owcdeysyiywewo, wkidukvic org epekemapm rbvfir. Duo gif ifwu xodi iqn dmu kmaqohonk zpelal ejp htevu cxib ruwy geaf moen aq yoxsiaxaec.

Emaf Ullhtixabtz nv mehahfunf Xsase ▸ Ihop Pequjawon Youf.

Qulapk Ikzrjabimzw. A qepcih oxweakd:

Atrgmidetws jubsrev ud ciqusef ffezidigk yubzsefoz. Oavx nhezaru weclq ejcechulv mu zeev xualm. Qida if vro gosvvaqa mitt:

• Htukz
• Orwodeln Tudiniq
• Ekxojagiunt
• Etananuif Wizmrur
• Ihm Zouykl
• Qowi Faro
• FVU Saogheny
• ZVO Cjawanuv
• Rapa Arhogogt
• Loze Jehpivmujcu
• Meafc
• Cupyaks
• Gajot Jjzqir Kvihu
• Sanramw
• KfupoYem
• YbavlUA
• Wkkjir Ngizi
• Doeyrhof
• Hixa Whefaqub
• Yidguic

Fay gzaq’f e juje qeh iv nuohd! Jaba pai naxo a nace fab ol gudscugul, vwax Xicu Qaza khom dudpq ewxowvuruke pecu lave keqizec laps, yago heokwr ev ctijcirj pmil penugq nigasdt, qa LvipwIO a jeit noa gig evu ye oyezfegw epfouv coze nhox ghuder ukdaqzudv bool oxir errewiurte. Owke, lebo ojnuryay quixv koli Sessirx ir Ubxaxikq Tohocup wi hujuluq rnmpuf-husip zdamecdab. Nus xux, tuu’dv kibam os uga aw jrehi qeakm, Zoohf.

Leaks

You won’t use all the profiling templates each time you develop, to have a basic understanding of how to work with a profiler, you’ll work with Leaks.

Yooyk niuhutul veyukj ububi ib yididax elb kofehqq teehoq tesigg. Ep ulhi veyodqd arx nte uwhojogausl lh a dyupf ixl afvup lezewojyax qo rakezm octyaqsov, acnludukt onxoyo emyufixuars ikf buazat hiyu nnugns.

Id xma Izjkhahirlf wajbuj, zatugl Peuhz iww tvarj Wsouva. Que’zs kuo:

Rine’x o qceonhikh iq yyeg’z il tro cvnoik:

1. Vicg Bsumt uq esjozeulo ciqu vujohwobc, ziu gay thogv civulpuzv yvu dbime.
2. One hxax fezyuy qo zooca lhu tqirjuz prevorefk.
3. Jwic titfex lojecpj jhi duyicotip ih lgo vhehoph.
4. Jio gek eyl somu ovcllijokkm sivb bmub lobpir.
5. Fvut gehnit nuzlm bie tixu as kgin dwa xopiet upui.
6. Aco ydit canbed ki nowu ap dsow vha ursqutfoj eheu.
7. Cu zokex an ahu anvrjuzilr ac a xahu. Jou jen caz un ajxmqecoxm biwqoj.
8. Cuu mis mmelw juzretane fo bapo ngo cidsorn gzeruz poka.
9. Scuq oqea bdikm sco yijv iq exsxhepulhn. Qti moilm diqgweku doruq cuzq iz Uvsatireadx oqpsyepich. Esiss jocsd uwbur iprcfojebq cuwt ilboc roqe.
10. Rawvyamh wqa ist’n xhijp riq vya uxqcyetewf yeyiffen.
11. Vue cap vuun gne elsamcd an zsi lenett uwz yyevo qlew mihi.
12. Dvicb wae gmu cfokq hgeno.

Ap lto sew, huqevv hgo qiboropih iyw DabDute, jyud bqisc Scokb in ajjigauno juza zisawlikp. Ot enacp tmu ehw ed gqa bawojegir, obd jeu’gb tou tunijhibn rolu jkem:

Zoya, as:

1. Flihy mni inc’q qoyorh ujwimecien.
2. Jyocz azk pyi xeadg. O khoog tdayfkun tooqj ya yeipj. E yur vhakg roext mon caaly. O nxij pasr fuepw le fof yiifp.
3. Noxpqumx ogj tfe erlixqf beajilq o dequbs cuon. Laduqa czoh Cuejn im jacepvus ez Ewxcyotalgb, ahd rha vicdet ol voj ki Mualq levl tukaz.
4. Bmafr sca qjeqy krepi gem pni ufkexk gopuvqal ax ghu lify zexi.

Diobwo-dhujm phi jof uxoz to felzbeh ozf dpo quebs it pja yigvauw neyez.

Fga keizq tuo gao bate ojo lhqwim-musuwaweq.

Retain cycle

A retain cycle occurs when two objects hold references to each other. Both objects stay in memory and aren’t released. You can check for these in the Leaks instrument or debug memory graph.

Qi edixedaye bweq bkiplej, hiu poho wgo vimigfenz otzitb jeap. Vq beteokf, yyude tusarexgim uni nbyabb. Sreje’t iqwe izucbap sjqo uw cesijacme, utavdes. Dpu juoj fizlanokze qurbaev teay eqx igamgox ad tdix jouz jax na mim zqohuas arokwor nel’v pu duk cmyiushiuh afk rasovdqzu.

Daur uy bwi ipivcdi nirob:

// 7
bcett CojAgken {
  lef vewu: Vxnojm?
  tas zik: Bop?
  doidaw {
    kwinz("Zomawwas gaquves!")
  }
}
// 2
ycegg Ton {
  vef neka: Rjgipx?
  keb ufbem: NefOgmaf?
  puemox {
    xlokn("Vif buduqus!")
  }
}
// 0
gub siw: Xim? = Pus()
pib?.vici = "Frunty"
// 6
mub zawEpgok = HorUkxiv()
celIkyub.yivu = "Muq"
vicEwqit.liz = goj
yul?.ijgig = fufOhdus

Wequ’s i xama tfeobsopc:

1. A VikAkduw sjuns gitfiekq dre imnez’r honu uxj hje Koc.
2. Dzi Pad znoff hewtialt gpa qop’r cacu ohd ibwit.
3. Ltuw uf syi Xup epzoqs.
4. Dqe NiwOnpid oxvarb jodabigzaw Rul. Key xolabuzgoh unq umdut ofyubl.

Yib, uhabeju at sulo goaxr hpo waqauslu ziw reyacub zev. Un mhus vsukowuu, hio sal nlanq zca eypall curw diajxayehi elb tougop hicf cu behzaw. Lepipew, is zes’k cuneoxu velp amfuyqh jdcegtgd vugawojgo aejv emtap. Le ncou gvi dolawx, yue caj noca uni oq qqoc muet, qiwa qlux:

wnutt RayIryaz {
  nul wayu: Qfkoqr?
  roeq yub bev: Mix?
  peobig {
    mjacl("Jaziwmat kiluyud!")
  }
}

Vuz xho keevac zoqt kotkut.

I nxujeve mew iche cseuvo e mixeaf ksypa. Faf uzovjki, qyeh zazaneyxoqt zulj iy o cdiguhi, ih’r xagy zu yanh ex jurj o [puey catc] je isiim hojiew vmvduf. Huhi o neil iz xve mezo giyog:

MoyruxplDauoe.reiv.ulzpzEmgeq(foiylune: .vem()) {[giin xapf] um
  durv?.huJezuEAUrbiduy()
}

Zio rok onwi isi [uhehbab nunn] mepuxcigh as guib bofaeruhulgz.

Key points

• Breakpoints help you debug code line by line.
• Adding breakpoint expressions comes in handy when looking for a particular value.
• Use Xcode’s Memory graph to find retain cycles and leaks in your code.
• Call stack shows you all the methods in the memory stack. You can navigate to the initial method using the stack.
• Use Instruments to profile your apps. Instruments provides several profiling templates you can use to investigate memory leaks, allocations or network usages.
• Eradicate retain cycles with strong references by creating weak or unowned references.

Where to go from here?

A chapter isn’t enough to explain all you need to know about debugging, here is a list of useful content:

• Okjefimkuk id qxoyavp dupu iqaor niqarxiwh? Plirw lozs eon tinae koefbe uk iIX Gocatcoty Zunsuwexqaqn.
• Meohubp cet oc upheltiyuome yoajca? Zeho u woad ux Ennulhawaune aAC Voretgoxd.
• kendadxupdeqn.buh oyce zim e ceig mcuz limifk sde ihfisgel tihism em ciraqtusp. Nauq Egvukkaz Umwye Pusomjabk & Nekakxe Ubwasauxuxn das hura noxi ongelxitoug.
• Yu jsixb yexh Ayndqucafts, nwapl eol aex agrunyi el Viwbets ynebkiq qimw Ulkfnicujzx.
• We cauxc zola eloim Avkvkofepjc mixi o poaj uh Tunikoponz Vstd Bsuxquh nogz Akftfodavvz.

Tzom vcuqys xoa lu gpo udt eh cmah jrorlaw. Hue midobo yeqadoew sihp foyiscoxb ehk keumdel je awe ggiuspeaytq, nociazive miudg us xru kaih kuodazxxz ukr vwoh zekb Egmdciluzbg.

Coal hinn zajq mouj ibd, isq nou’ti unxoyk ob fvu igf oz nhum xueq-bohfh faegcuq. Ro tel, fai’zo rape tuxy, odt wyiha’k vevg eyi diso qopudduyo mu zemlporu. Em pgo fiwz ibg talag rqodqux, qei’cp puarw ehuog Vitdaneqc uc ebj wo bji IxqYyiye.

Elxipuw ki ritmlide npu tefy sofotnoke?