NSMutableArray+WDMutableArray.m

#import "NSMutableArray+WDMutableArray.h"
#import <objc/runtime.h>

@implementation NSMutableArray (WDMutableArray)

+ (void)load {
    Method fromMethod = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(objectAtIndex:));
    Method toMethod = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(wd_objectAtIndex:));
    method_exchangeImplementations(fromMethod, toMethod);
}

// 为了避免和系统的方法冲突，我一般都会在swizzling方法前面加前缀
- (id)wd_objectAtIndex:(NSUInteger)index {
    // 判断下标是否越界，如果越界就进入异常拦截
    if (self.count-1 < index) {
        @try {
            return [self wd_objectAtIndex:index];
        }
        @catch (NSException *exception) {
            // 在崩溃后会打印崩溃信息。
            NSLog(@"---------- %s Crash Because Method %s  ----------\n", class_getName(self.class), __func__);
            NSLog(@"%@", [exception callStackSymbols]);
            
            
            return nil;
        }
        @finally {}
    } // 如果没有问题，则正常进行方法调用
    else {
        return [self wd_objectAtIndex:index];
    }
}

@end