今天学习了一下ObjC Runtime，以前都是在Xcode里面写代码，都是工具自动搞定了，今天体验了一下命令行：

#import <Foundation/Foundation.h>

@interface MyObject : NSObject
{
 NSString *aString;
}

@property(retain) NSString *aString;

@end

@implementation MyObject

-(id)init
{
 if (self = [super init]) {
  [self setAString:nil];
 }
 return self;
}

@synthesize aString;

@end



int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

 id obj1 = [NSMutableArray alloc];
 id obj2 = [[NSMutableArray alloc] init];

 id obj3 = [NSArray alloc];
 id obj4 = [[NSArray alloc] initWithObjects:@"Hello",nil];

 NSLog(@"obj1 class is %@",NSStringFromClass([obj1 class]));
 NSLog(@"obj2 class is %@",NSStringFromClass([obj2 class]));

 NSLog(@"obj3 class is %@",NSStringFromClass([obj3 class]));
 NSLog(@"obj4 class is %@",NSStringFromClass([obj4 class]));

 id obj5 = [MyObject alloc];
 id obj6 = [[MyObject alloc] init];

 NSLog(@"obj5 class is %@",NSStringFromClass([obj5 class]));
 NSLog(@"obj6 class is %@",NSStringFromClass([obj6 class]));

 [pool drain];
    return 0;
}

在命令行中，我们可以直接编译：

gcc -ObjC -framework Foundation b.m
 ./a.out

或者为了方便查看，可以一步步来：

//第一步，预处理：我们可以发现，Foundation.h被展开了
 gcc -ObjC b.m -E -o b.i
 //第二部，编译成汇编代码：生成的b.s就是纯正的汇编语言代码
 gcc -ObjC -S b.i
 //第三步，汇编:我们可以查看b.o
 gcc -c b.s
 //第四步，链接：生成a.out，或者通过-o改变输出文件名
 gcc -ObjC -framework Foundation b.o

# update 2014-11-25

把objc代码翻译成Cpp

clang -rewrite-objc block.c