[英]What is the purpose of the flags struct in iOS?
struct
{
unsigned resizesCellWidths:1;
unsigned numColumns:6;
unsigned separatorStyle:3;
unsigned allowsSelection:1;
unsigned backgroundViewExtendsUp:1;
unsigned backgroundViewExtendsDown:1;
unsigned usesPagedHorizontalScrolling:1;
unsigned updating:1;
unsigned ignoreTouchSelect:1;
unsigned needsReload:1;
unsigned allCellsNeedLayout:1;
unsigned isRotating:1;
unsigned clipsContentWidthToBounds:1;
unsigned isAnimatingUpdates:1;
unsigned requiresSelection:1;
unsigned contentSizeFillsBounds:1;
unsigned delegateWillDisplayCell:1;
unsigned delegateWillSelectItem:1;
unsigned delegateWillSelectItemMultiTouch:1;
unsigned delegateWillDeselectItem:1;
unsigned delegateDidSelectItem:1;
unsigned delegateDidSelectItemMultiTouch:1;
unsigned delegateDidDeselectItem:1;
unsigned delegateGestureRecognizerActivated:1;
unsigned delegateAdjustGridCellFrame:1;
unsigned delegateDidEndUpdateAnimation:1;
unsigned dataSourceGridCellSize:1;
unsigned int isEditing:1;
unsigned __RESERVED__:1;
} _flags;
:1
表示什么? unsigned
修飾符是什么意思? 謝謝
那些是位域 。 由於大多數都是標志,因此它們只有2個可能的值,因此無需為每個字段分配超過1位的值。 (該結構中有幾個例外)
unsigned
可以單獨作為一種類型。 這只是一個unsigned int
。
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