iOS中手动忽略编译警告

• 忽略警告

  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "相关命令"
  // 这是是出现警告的代码
  #pragma clang diagnostic pop

常见的命令有
1.方法废弃

#pragma clang diagnostic push  
#pragma clang diagnostic ignored "-Wdeprecated-declarations"      
//废弃的方法
#pragma clang diagnostic pop

2.不兼容指针类型

#pragma clang diagnostic push   
#pragma clang diagnostic ignored "-Wincompatible-pointer-types"  
//
#pragma clang diagnostic pop

3.未使用变量

#pragma clang diagnostic push     
#pragma clang diagnostic ignored "-Wunused-variable"     
int a;     
#pragma clang diagnostic pop

4.

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
[observer performSelector:selector withObject:notification];
#pragma clang diagnostic pop

如果需要每个属性或每个方法都去指定nonnull和nullable，是一件非常繁琐的事。苹果为了减轻我们的工作量，专门提供了两个宏:

NS_ASSUME_NONNULL_BEGIN

NS_ASSUME_NONNULL_END