iOS 15 更新学习笔记 （1）

1、json解析支持json5了

typedef NS_OPTIONS(NSUInteger, NSJSONReadingOptions) {
    NSJSONReadingMutableContainers = (1UL << 0),
    NSJSONReadingMutableLeaves = (1UL << 1),
    NSJSONReadingFragmentsAllowed = (1UL << 2),

    NSJSONReadingJSON5Allowed API_AVAILABLE(macos(12.0), ios(15.0), watchos(8.0), tvos(15.0)) = (1UL << 3),
    NSJSONReadingTopLevelDictionaryAssumed API_AVAILABLE(macos(12.0), ios(15.0), watchos(8.0), tvos(15.0)) = (1UL << 4),

    NSJSONReadingAllowFragments API_DEPRECATED_WITH_REPLACEMENT("NSJSONReadingFragmentsAllowed", macos(10.7, API_TO_BE_DEPRECATED), ios(5.0, API_TO_BE_DEPRECATED), watchos(2.0, API_TO_BE_DEPRECATED), tvos(9.0, API_TO_BE_DEPRECATED)) = NSJSONReadingFragmentsAllowed,
} API_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0));

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json5示例：

{
  // comments
  unquoted: 'and you can quote me on that',
  singleQuotes: 'I can use "double quotes" here',
  lineBreaks: "Look, Mom! \
No \\n's!",
  hexadecimal: 0xdecaf,
  leadingDecimalPoint: .8675309, andTrailing: 8675309.,
  positiveSign: +1,
  trailingComma: 'in objects', andIn: ['arrays',],
  "backwardsCompatible": "with JSON",
}

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支持注释、key不必须双引号等等；

2、对状态编程的支持：UICellConfigurationState；UICollectionViewCell、UITableViewCell都支持状态变化时的block执行了。

3、UICollectionViewLayout支持自动高度；AutomaticDimension