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:
                                            addDenominator:];
         [f1 print];

         Fraction *f2 = [[Fraction alloc]initWithNumerator:
                                            addDenominator:];
         [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[] = {c1,f1,@""};
           for(int i=;i<;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 ;
 }