OC 项目全局防止因NSArray,NSDictionary,NSObject为nil的时候引起的崩溃

常见错误：

NSInvalidArgumentException

-[NSNull containsString:]: unrecognized selector sent to instance 0x1f4db9c00xxxx + 229708

[__NSArrayM objectAtIndexedSubscript:]: index 1 beyond bounds for empty arrayxxx + 554240

（防止数据为空引起崩溃）

第一步：

https://github.com/nicklockwood/NullSafe

下载这个Demo，只要将其中的NullSafe.m文件移到依赖的工具包里面即可，不需要引用，它有运行时自引用（#import <objc/runtime.h>会运行时自引用）。

第二步：

可以通过下面代码测出：[NSNull containsString:]这个bug。

代码如下：

NSMutableDictionary *tempDict = [NSMutableDictionary new];

[tempDict setObject:[NSNull null] forKey:@"strv"];

    if([tempDict[@"strv"] containsString:@"A"]){

}

（防止数据越界引起崩溃）

第三步：

增加这个NSArray+BeyondIntercept.m文件，不需要引用，它有运行时自引用（#import <objc/runtime.h>会运行时自引用）。

第四步：NSArray+BeyondIntercept.m文件的具体代码

#import <objc/runtime.h>

#import <Foundation/Foundation.h>

// 防止数据越界

@implementation NSArray (BeyondIntercept)

+ (void)load {

    Method oldObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayI"), @selector(objectAtIndex:));

    Method newObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayI"), @selector(newObjectAtIndex:));

    method_exchangeImplementations(oldObjectAtIndex, newObjectAtIndex);

    

    Method oldMutableObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayI"), @selector(objectAtIndexedSubscript:));

    Method newMutableObjectAtIndex =  class_getInstanceMethod(objc_getClass("__NSArrayI"), @selector(newObjectAtIndexedSubscript:));

    method_exchangeImplementations(oldMutableObjectAtIndex, newMutableObjectAtIndex);

    

    Method oldMObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(objectAtIndex:));

    Method newMObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(newMutableObjectAtIndex:));

    method_exchangeImplementations(oldMObjectAtIndex, newMObjectAtIndex);

    

    Method oldMMutableObjectAtIndex = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(objectAtIndexedSubscript:));

    Method newMMutableObjectAtIndex =  class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(newMutableObjectAtIndexedSubscript:));

    method_exchangeImplementations(oldMMutableObjectAtIndex, newMMutableObjectAtIndex);

}

- (id)newObjectAtIndex:(NSUInteger)index {

    @try {

        return [self newObjectAtIndex:index];

    } @catch (NSException * exception) {

        NSLog(@"Fatal: %@ %@", exception.name, exception.reason);

        return nil;

    }

}

- (id)newObjectAtIndexedSubscript:(NSUInteger)index {

    @try {

        return [self newObjectAtIndexedSubscript:index];

    } @catch (NSException *exception) {

        NSLog(@"Fatal: %@ %@", exception.name, exception.reason);

        return nil;

    }

}

- (id)newMutableObjectAtIndex:(NSUInteger)index {

    @try {

        return [self newMutableObjectAtIndex:index];

    } @catch (NSException *exception) {

        NSLog(@"Fatal: %@ %@", exception.name, exception.reason);

        return nil;

    }

}

- (id)newMutableObjectAtIndexedSubscript:(NSUInteger)index {

    @try {

        return [self newMutableObjectAtIndexedSubscript:index];

    } @catch (NSException *exception) {

        NSLog(@"Fatal: %@ %@", exception.name, exception.reason);

        return nil;

    }

}

@end

更多开发问题，可加V。感谢同事帮我解决了问题。