iphone - What does [super viewWillAppear] do, and when is it required? -

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  - (शून्य) दृश्यविलएपीपर: (BOOL) एनिमेटेड {// यहाँ कुछ [सुपर दृश्यवैलप्रदर्शक]; }

क्या [super viewWillAppear] हमेशा आवश्यक है? यदि नहीं, तो कब और क्यों इसका इस्तेमाल करते हो?

सबसे पहले, सही बॉयलर प्लेट होना चाहिए:

<पूर्व> - (शून्य) दृश्यविलएपीपर: (BOOL) एनिमेटेड {[सुपर व्यूव्वलएपपर: एनिमेटेड]; // कुछ यहाँ}

दूसरे शब्दों में, सुपर पहले को कॉल करें, फिर अपनी खुद की बात करें और आपको एनिमेटेड पैरामीटर को सुपर पास करना होगा।

आप आमतौर पर किसी भी तरीके से पहले सुपर क्लास कार्यान्वयन को कॉल करना चाहते हैं। कई भाषाओं में यह आवश्यक है उद्देश्य-सी में यह नहीं है, लेकिन आप आसानी से परेशानी में चल सकते हैं यदि आप इसे अपनी विधि के शीर्ष पर नहीं डालते हैं। (उसने कहा, मैं कभी-कभी इस पद्धति को तोड़ता हूं।)

क्या super's कार्यान्वयन आवश्यक है? इस विशेष पद्धति के मामले में आप अप्रत्याशित व्यवहार प्राप्त कर सकते हैं यदि आप इसे कॉल नहीं करते हैं (विशेषकर यदि आपने UINavigationController को उप-वर्ग किया है उदाहरण के लिए) तो इसका जवाब है नहीं तकनीकी अर्थों में नहीं है, लेकिन आपको शायद हमेशा ऐसा करना चाहिए।

हालांकि, कई अन्य तरीकों में कॉलिंग नहीं करने के अच्छे कारण हो सकते हैं सुपर ।


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