#pragma处理警告

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//
//  ViewController.m
//  pragma
//
//  Created by Code_Hou on 2017/3/30.
//  Copyright © 2017年 侯森魁. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

/*
 #pragma 在本质上是声明，常用的功能就是注释，尤其是给Code分段注释；然而它还有另外一个强大的功能是处理编译器警告.
 
 clang diagnostic 是#pragma 第一个常用命令:
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-相关命令"
   //自己的代码
 #pragma clang pop
 */
- (void)viewDidLoad {
    [super viewDidLoad];
    //取消方法启用的警告
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"1" message:@"2" delegate:nil cancelButtonTitle:@"3" otherButtonTitles:@"4", nil];
   [alert show];
#pragma clang diagnostic pop
    
    //取消不兼容指针类型警告
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wincompatible-pointer-types"
    //
#pragma clang diagnostic pop
    
    
    //取消循环引用的警告
    // completionBlock is manually nilled out in AFURLConnectionOperation to break the retain cycle.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-retain-cycles"
//    self.completionBlock = ^ {
//        ...
//    };
#pragma clang diagnostic pop
    

    //取消未使用变量的警告
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-variable"
    int a;
#pragma clang pop
    
    // Do any additional setup after loading the view, typically from a nib.
}

/*
 #pargma 用法详情：
 
 http://nshipster.cn/pragma/
 http://nshipster.com/clang-diagnostics/
 http://fuckingclangwarnings.com/
 http://clang.llvm.org/docs/UsersManual.[html](http://www.2cto.com/kf/qianduan/css/)#diagnostics_pragmas
 
 
 */

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end