防止数组越界处理

1、不可变数组

#import "NSArray+ArrayCheck.h"
#import <objc/runtime.h>
@implementation NSArray (ArrayCheck)
+ (void)load{
    
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Method fromMethod = class_getInstanceMethod(objc_getClass("__NSArrayI"), @selector(objectAtIndex:));
        Method toMethod = class_getInstanceMethod(objc_getClass("__NSArrayI"), @selector(objectAtIndexCheck:));
        method_exchangeImplementations(fromMethod, toMethod);
    });
}


- (id)objectAtIndexCheck:(NSUInteger)index {
    if (self.count-1 < index) {
        // 异常处理
        @try {
            return [self objectAtIndexCheck:index];
        }
        @catch (NSException *exception) {
            // 打印崩溃信
            NSLog(@"---------- %s Crash Because Method %s  ----------\n", class_getName(self.class), __func__);
            NSLog(@"不可变数组异常%@", [exception callStackSymbols]);
            return nil;
        }
        @finally {}
    } else {
        return [self objectAtIndexCheck:index];
    }
}
@end

 2、可变数组

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

@implementation NSMutableArray (ArrayMCheck)

+ (void)load{
    
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Method fromMethod = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(objectAtIndex:));
        Method toMethod = class_getInstanceMethod(objc_getClass("__NSArrayM"), @selector(objectAtIndexCheck:));
        method_exchangeImplementations(fromMethod, toMethod);
    });
}


- (id)objectAtIndexCheck:(NSUInteger)index {
    if (self.count-1 < index) {
        // 异常处理
        @try {
            return [self objectAtIndexCheck:index];
        }
        @catch (NSException *exception) {
            // 打印崩溃信息
            NSLog(@"---------- %s Crash Because Method %s  ----------\n", class_getName(self.class), __func__);
            NSLog(@"可变数组异常%@", [exception callStackSymbols]);
            return nil;
        }
        @finally {}
    } else {
        return [self objectAtIndexCheck:index];
    }
}
@end

 参考链接：http://www.jianshu.com/p/ff19c04b34d0