Data Formatting Guide.pdf

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1、DataFormattingGuideContentsIntroductiontoDataFormattingProgrammingGuideForCocoa4OrganizationofThisDocument4NumberFormatters5UseFormatterStylestoPresentNumbersWiththeUser’sPreferences5UseFormatStringstoSpecifyCustomFormats6Percentages7Nomenclature7DateFormatters8Us

2、eFormatterStylestoPresentDatesandTimesWiththeUser’sPreferences8UseFormatStringstoSpecifyCustomFormats9FixedFormats9CustomFormatsforUser-VisibleDates10ParsingDateStrings12CacheFormattersforEfficiency13ConsiderUnixFunctionsforFixed-Format,UnlocalizedDates15Formatter

3、sandUserInterfaceElements16AssociatingaFormatterWithaCell16DelegationMethodsforErrorHandling17CreatingaCustomFormatter18DocumentRevisionHistory192012-09-19

4、Copyright©2012AppleInc.AllRightsReserved.2ListingsNumberFormatters5Listing1Formattinganumberusingaformatters

5、tyle5Listing2Formattinganumberusingaformatstring6DateFormatters8Listing1Formattingadateusingformatterstyles9Listing2ParsinganRFC3339date-time12Listing3ParsinganRFC3339date-timeusingacachedformatter132012-09-19

6、Copyright©2012AppleInc.AllRightsReserved.3Introduction

7、toDataFormattingProgrammingGuideForCocoaYouuseformatterstointerpretandcreatestringsthatrepresentotherdatatypes,andtovalidatethetextintextfieldsandothercells.Formattersareinstancesofsubclassesoftheabstractclass,NSFormatter.TheFoundationframeworkprovidestwoconcretes

8、ubclassesofNSFormatter:NSNumberFormatterandNSDateFormatter.(CoreFoundationprovidestwoequivalentopaquetypes:CFNumberFormatterandCFDateFormatter.Thesearesimilarbutarenottoll-freebridged.)YoucancreateasubclassofNSFormatterforcustomformatting.Youshouldreadthisdocument

9、togainabasicunderstandingofhowtocreateandusedateandnumberformatters,andhowyoucancreateacustomformatterobject.OrganizationofThisDocument“DateFormatters”(page8)describeshowtousedateformatters.“NumberFormatters”(page5)describeshowtousenumberformatters.“FormattersandU

10、serInterfaceElements”(page16)describeshowtosetaformatterforauserinterfaceelement,andtheinteractionbetweenanelementanditsformatterinOSX.“CreatingaCustomF