Objective-C 语法之 Debug 表达式

main.m

 #import <Foundation/Foundation.h>
 #import "TestClass.h"

 int main(int argc, const char * argv[]) {
     @autoreleasepool {
         NSString *purposeInfo = @"拿到的信息不仅在Debug中有用，而且在selector的传递也很有用";
         [TestClass testDebugKeyword:purposeInfo];
     }
     return ;
 }

TestClass.h

 #import <Foundation/Foundation.h>

 @interface TestClass : NSObject
 + (void)testDebugKeyword:(NSString *)purposeInfo;

 @end

TestClass.m

 #import "TestClass.h"

 @implementation TestClass

 + (void)testDebugKeyword:(NSString *)purposeInfo {
     NSMutableString *mStrInfo = [[NSMutableString alloc] initWithString:purposeInfo];
     [mStrInfo appendString:@"\n\nDebug时一些系统预留定义词的用法如下：\n"];
     [mStrInfo appendFormat:@"__func__: %s\n", __func__];
     [mStrInfo appendFormat:@"__PRETTY_FUNCTION__: %s\n", __PRETTY_FUNCTION__];
     [mStrInfo appendFormat:@"__LINE__: %d\n", __LINE__];
     [mStrInfo appendFormat:@"__FILE__: %s\n", __FILE__];

     [mStrInfo appendString:@"\n\nDebug时一些Core Foundation方法的用法如下：\n"];
     [mStrInfo appendFormat:@"NSStringFromSelector(_cmd): %@\n", NSStringFromSelector(_cmd)];
     [mStrInfo appendFormat:@"NSStringFromClass([self class]): %@\n", NSStringFromClass([self class])];
     [mStrInfo appendFormat:@"[[NSString stringWithUTF8String:__FILE__] lastPathComponent]: %@\n", [[NSString stringWithUTF8String:__FILE__] lastPathComponent]];

     NSLog(@"%@", mStrInfo);
 }

 @end

结果：

 -- ::16.353 OCDebugKeyword[:] 拿到的信息不仅在Debug中有用，而且在selector的传递也很有用

 Debug时一些系统预留定义词的用法如下：
 __func__: +[TestClass testDebugKeyword:]
 __PRETTY_FUNCTION__: +[TestClass testDebugKeyword:]
 __LINE__:
 __FILE__: /Users/Kenmu/Documents/iOSDevelopment/OCDebugKeyword/OCDebugKeyword/TestClass.m

 Debug时一些Core Foundation方法的用法如下：
 NSStringFromSelector(_cmd): testDebugKeyword:
 NSStringFromClass([self class]): TestClass
 [[NSString stringWithUTF8String:__FILE__] lastPathComponent]: TestClass.m