1、创建一个SendCrash类
.h

//
//  SendCrash.h
//  Crash
//
//  Created by LC on 16/10/15.
//  Copyright © 2016年 LC. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface SendCrash : NSObject
//路径
+ (NSString *)getFilePath;
//崩溃回调
+ (void)setDefaultHandler;

+ (NSUncaughtExceptionHandler *)getHandler;
//写入
+ (void)TakeException:(NSException *) exception;
//删除
+ (void)deleteFile;
//读取
+ (NSString *)readFile;
@end

.m

//
//  SendCrash.m
//  Crash
//
//  Created by LC on 16/10/15.
//  Copyright © 2016年 LC. All rights reserved.
//

#import "SendCrash.h"

// 返回沙盒地址
NSString * applicationDocumentsDirectory()
{
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}

// 出现崩溃时的回调函数
void UncaughtExceptionHandler(NSException * exception)
{
    NSArray * arr = [exception callStackSymbols];
    NSString * reason = [exception reason]; // 崩溃的原因  可以有崩溃的原因(数组越界,字典nil,调用未知方法...) 崩溃的控制器以及方法
    NSString * name = [exception name];
    NSString * url = [NSString stringWithFormat:@"========异常错误报告========\nname:%@\nreason:\n%@\ncallStackSymbols:\n%@",name,reason,[arr componentsJoinedByString:@"\n"]];
    NSString * path = [applicationDocumentsDirectory() stringByAppendingPathComponent:@"Exception.txt"];
    // 将txt文件写入沙盒
    [url writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];
    
}

@implementation SendCrash

// 返回沙盒地址
+ (NSString *)getFilePath
{
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}

+ (void)setDefaultHandler
{
    NSSetUncaughtExceptionHandler(&UncaughtExceptionHandler);
}

+ (NSUncaughtExceptionHandler *)getHandler
{
    return NSGetUncaughtExceptionHandler();
}

+ (void)TakeException:(NSException *)exception
{
    NSArray * arr = [exception callStackSymbols];
    NSString * reason = [exception reason];
    NSString * name = [exception name];
    NSString * url = [NSString stringWithFormat:@"========异常错误报告========\nname:%@\nreason:\n%@\ncallStackSymbols:\n%@",name,reason,[arr componentsJoinedByString:@"\n"]];
    NSString * path = [applicationDocumentsDirectory() stringByAppendingPathComponent:@"Exception.txt"];
    [url writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];
    
    NSLog(@"11111");
}

// 删除沙盒里的文件
+ (void)deleteFile {
    NSFileManager* fileManager=[NSFileManager defaultManager];
    //文件名
    NSString *uniquePath = [applicationDocumentsDirectory() stringByAppendingPathComponent:@"Exception.txt"];
    BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];
    if (!blHave) {
        NSLog(@"no  have");
        return ;
    }else {
        NSLog(@" have");
        BOOL blDele= [fileManager removeItemAtPath:uniquePath error:nil];
        if (blDele) {
            NSLog(@"dele success");
        }else {
            NSLog(@"dele fail");
        }
        
    }
}

+ (NSString *)readFile
{
    // 拼接要写入文件的路径
    NSString *path = [applicationDocumentsDirectory() stringByAppendingPathComponent:@"Exception.txt"];
    // 从路径中读取字符串
    NSString *string = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
    NSLog(@"%@", string);
    return string;
}
@end

2、在AppDelegate.m里面添加如下代码：

//
//  AppDelegate.m
//  Crash
//
//  Created by LC on 16/10/15.
//  Copyright © 2016年 LC. All rights reserved.
//

#import "AppDelegate.h"
#import "SendCrash.h"
#import "ViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
#pragma mark -- 崩溃日志
    [SendCrash setDefaultHandler];
    // 发送崩溃日志
    NSString *path = [SendCrash getFilePath];
    NSString *dataPath = [path stringByAppendingPathComponent:@"Exception.txt"];
    NSData *data = [NSData dataWithContentsOfFile:dataPath];
    if (data != nil) {
        [self sendExceptionLogWithData:data];
    }
    
    return YES;
}

#pragma mark -- 发送崩溃日志
- (void)sendExceptionLogWithData:(NSData *)data
{
    NSURL*url=[NSURL URLWithString:@"prefs:root=LOCATION_SERVICES"];
    
    [[UIApplication sharedApplication] openURL:url];
    
    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    manager.requestSerializer.timeoutInterval = 5.0f;
    //告诉AFN，支持接受 text/xml 的数据
    [AFJSONResponseSerializer serializer].acceptableContentTypes = [NSSet setWithObject:@"text/plain"];
    NSString *urlString = @"后台地址";
    
    [manager POST:urlString parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData>  _Nonnull formData) {
        [formData appendPartWithFileData:data name:@"file" fileName:@"Exception.txt" mimeType:@"txt"];
    } success:^(NSURLSessionDataTask * _Nonnull task, id  _Nonnull responseObject) {
       
    } failure:^(NSURLSessionDataTask * _Nonnull task, NSError * _Nonnull error) {
        
    }];
}