NSDictionaryOfVariableBindings

最新推荐文章于 2025-11-30 11:11:41 发布

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这篇博客介绍了宏定义`NSDictionaryOfVariableBindings`的用途，它用于辅助创建用于`constraintsWithVisualFormat:options:metrics:views:`的方法中的视图字典。通过这个宏，可以便捷地将变量与对应的键值对匹配，简化了iOS界面布局的代码编写过程。

/* This macro is a helper for making view dictionaries for +constraintsWithVisualFormat:options:metrics:views:.
 NSDictionaryOfVariableBindings(v1, v2, v3) is equivalent to [NSDictionary dictionaryWithObjectsAndKeys:v1, @"v1", v2, @"v2", v3, @"v3", nil];
 */
#define NSDictionaryOfVariableBindings(...) _NSDictionaryOfVariableBindings(@"" # __VA_ARGS__, __VA_ARGS__, nil)
NSLAYOUTCONSTRAINT_EXTERN NSDictionary<NSString *, id> *_NSDictionaryOfVariableBindings(NSString *commaSeparatedKeysString, __nullable id firstValue, ...) API_AVAILABLE(macos(10.7), ios(6.0)); // not for direct use

 param = NSDictionaryOfVariableBindings(key1, key2, key3);

/* This macro is a helper for making view dictionaries for +constraintsWithVisualFormat:options:metrics:views:.
NSDictionaryOfVariableBindings(v1, v2, v3) is equivalent to [NSDictionary dictionaryWithObjectsAndKeys:v1, @"v1", v2, @"v2", v3, @"v3", nil];
*/

该宏就是调用 constraintsWithVisualFormat:options:metrics:views:. 方法直接将Key和value字符值一样