Objective-C：异常的处理

//
//  main.m
//  03-动态绑定
//
//  Created by mac on 15/8/11.
//  Copyright (c) 2015年. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Fraction.h"
#import "Complex.h"
#import "MyException.h"
int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
        //测试分数类
        Fraction *f1 = [[Fraction alloc]initWithNumerator:1
                                           addDenominator:2];
        [f1 print];
        
        Fraction *f2 = [[Fraction alloc]initWithNumerator:2
                                           addDenominator:3];
        [f2 print];
        
        Fraction *f3 = [f1 add:f2];
        [f3 print];
        
        //测试复数类
        Complex *c1 = [[Complex alloc]initWithReal:5.0 andImag:3.0];
        [c1 print];
        
        Complex *c2 = [[Complex alloc]initWithReal:4.3 andImag:2.5];
        [c2 print];
        
        Complex *c3 = [c1 add: c2];
        [c3 print];
        
        
        //测试动态绑定
        id pObj = nil;
        pObj = f3;
        [f3 print];
        
        pObj = c3;
        [c3 print];
        
        MyException *pe;
        @try//将容易出现异常的代码放在try代码块里面
        {
          id arr[3] = {c1,f1,@""};
          for(int i=0;i<3;i++)
          {
              [arr[i] print];
              pe = [[MyException alloc] initWithName:@"MyException" reason:@"test" userInfo:nil];
              @throw pe;//主动抛出自定义的异常
          }
            NSLog(@"try last statement");//在出现异常后会跳过@try中后续的代码,不会执行。
        }
        @catch(MyException *e)//捕捉自定义的异常
        {
            NSLog(@"MyException:%@",[e reason]);
        }
        @catch(NSException *e)//系统捕捉异常
        {
            NSLog(@"%@",[e reason]);
        }
        @finally//最终处理
        {
            NSLog(@"finally");
        }
        //异常处理完,后续代码会继续执行
        NSLog(@"last statement!");
    }
    return 0;
}