Kev xaiv chaining thiab xaiv kev khi yog dab tsi?
Kev xaiv chaining thiab xaiv kev khi yog dab tsi?

Video: Kev xaiv chaining thiab xaiv kev khi yog dab tsi?

Video: Kev xaiv chaining thiab xaiv kev khi yog dab tsi?
Video: yog hmoov dab tsi. Zoo Xyooj (cover) 2024, Kaum ib hlis
Anonim

Xaiv kev khi khaws cov khoom koj nyob kev khi hauv qhov sib txawv. Hauv qhov no, nws yog navigationController. Ntawm qhov tod tes, xaiv chaining tsis muab tus nqi ntawm sab laug rau hauv qhov sib txawv.

Ib sab ntawm qhov no, dab tsi yog kev xaiv chaining thiab kev xaiv khi hauv Swift?

Cov txheej txheem ntawm querying, hu rau cov khoom, subscripts thiab cov txheej txheem ntawm ib xaiv tau uas tej zaum yuav yog 'nil' yog txhais raws li xaiv chaining . Kev xaiv chaining rov qab ob qhov tseem ceeb - yog tias xaiv tau muaj 'tus nqi' ces hu rau nws cov khoom muaj feem xyuam, txoj hauv kev thiab cov ntawv sau rov qab muaj nuj nqis.

Qhov thib ob, kuv puas tuaj yeem siv txoj hlua khi? Koj tuaj yeem siv kev xaiv chaining thaum sim hu ib txoj kev uas tej zaum yuav tsis muaj nyob. Qhov no ua tau yuav pab tau, piv txwv li, thaum siv API nyob rau hauv uas ib txoj kev yuav tsis muaj, txawm yog vim muaj hnub nyoog ntawm kev siv los yog vim muaj ib tug feature uas tsis muaj nyob rau ntawm tus neeg siv lub cuab yeej.

Dhau li ntawm no, dab tsi xaiv los khi?

Koj siv xaiv los khi mus xyuas seb cov xaiv tau muaj tus nqi lossis tsis. Yog hais tias nws muaj ib tug nqi, unwrap nws thiab muab tso rau hauv ib ntus tas li los yog txawv txav.

Kev xaiv chaining Swift yog dab tsi?

Kev xaiv chaining yog txheej txheem rau querying thiab hu cov khoom, txoj kev, thiab subscripts ntawm ib xaiv tau uas tej zaum tam sim no tsis yog. Yog tias xaiv tau muaj tus nqi, cov cuab yeej, txoj kev, lossis subscript hu ua tiav; yog tias xaiv tau yog nil, cov cuab yeej, txoj kev, lossis subscript hu rov qab nil.

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