背景

最近上線項(xiàng)目中使用UIVisualEffectView（高斯模糊）出現(xiàn)[<__NSArrayI 0x17000b630> valueForUndefinedKey:]: this class is not key value coding-compliant for the key gaussianBlur.錯(cuò)誤
初始化時(shí)出現(xiàn)下面錯(cuò)誤：

錯(cuò)誤日志.png

使用以下初始化方法：

- (UIVisualEffectView *)effectView{
    if(!_effectView){
        _effectView = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleDark]];
    }
    return _effectView;
}

該錯(cuò)誤主要在ios8系統(tǒng)下才會(huì)出現(xiàn)的個(gè)別情況。查找了一些資料，該問題應(yīng)該是系統(tǒng)bug. 那么就想如何避免該類型的報(bào)錯(cuò)導(dǎo)致crash.

處理方法

使用kvc和runtime機(jī)制防止程序出現(xiàn)意外的UnknownException類型的錯(cuò)誤。(轉(zhuǎn)移特定類型，如NSArray的valueForUndefinedKey: 和 setValue:forUndefinedKey:的具體實(shí)現(xiàn))

實(shí)現(xiàn)

為NSObject添加分類：NSObject+VFUK.
在分類中實(shí)現(xiàn)自定義實(shí)現(xiàn)過程：
NSObject+VFUK.h

//
//  NSObject+VFUK.h
//  BlockRedpag
//
//  Created by 何其燦 on 2019/1/3.
//  Copyright ? 2019 Lixiaoqian. All rights reserved.
//  處理系統(tǒng) valueForUndefinedKey:錯(cuò)誤

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface NSObject (VFUK)

///自定義valueForUndefinedKey:實(shí)現(xiàn)
+ (void)addCustomValueForUndefinedKeyImplementation:(IMP)handler;

@end

NS_ASSUME_NONNULL_END

NSObject+VFUK.m實(shí)現(xiàn)：

//
//  NSObject+VFUK.m
//  BlockRedpag
//
//  Created by 何其燦 on 2019/1/3.
//  Copyright ? 2019 Lixiaoqian. All rights reserved.
//

#import "NSObject+VFUK.h"
#import <CoreData/CoreData.h>
#import <objc/message.h>

@implementation NSObject (VFUK)

+ (void)addCustomValueForUndefinedKeyImplementation:(IMP)handler{
    Class clazz = self;
    if (clazz == nil) {
        return;
    }
    if (clazz == [NSObject class] || clazz == [NSManagedObject class])
  {
        return;
    }
    
    SEL vfuk = @selector(valueForUndefinedKey:);
    SEL svfuk = @selector(setValue:forUndefinedKey:);
    
    @synchronized([NSObject class]){
        Method nsoMethod = class_getInstanceMethod([NSObject class], vfuk);
        Method nsmoMethod = class_getInstanceMethod([NSManagedObject class], vfuk);
        Method origMethod = class_getInstanceMethod(clazz, vfuk);
        
        Method set_nsoMethod = class_getInstanceMethod([NSObject class], svfuk);
        Method set_nsmoMethod = class_getInstanceMethod([NSManagedObject class], svfuk);
        Method set_origMethod = class_getInstanceMethod(clazz, svfuk);
        
        
        if (set_origMethod != set_nsoMethod && set_origMethod != set_nsmoMethod) {
            return;
        }
        if (origMethod != nsoMethod && origMethod != nsmoMethod) {
            return;
        }
        
        if(!class_addMethod(clazz, svfuk, handler, method_getTypeEncoding(set_nsmoMethod))) {
        }
        
        if(!class_addMethod(clazz, vfuk, handler, method_getTypeEncoding(nsoMethod))) {
        }
    }
    
}

@end

實(shí)現(xiàn)以上類目后，在AppDelegate.m中對指定類型進(jìn)行轉(zhuǎn)移，如NSArray,NSString等。

static id UnknownExceptionKeyIMP(id self, SEL cmd, NSString* inKey)
{
    NSLog(@"exception key:%@,class:%@", inKey, [self class]);
    return nil;
}


@implementation AppDelegate

+ (void)initialize
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [NSArray addCustomValueForUndefinedKeyImplementation: (IMP)UnknownExceptionKeyIMP];
        [NSString addCustomValueForUndefinedKeyImplementation: (IMP)UnknownExceptionKeyIMP];
        [NSDictionary addCustomValueForUndefinedKeyImplementation: (IMP)UnknownExceptionKeyIMP];
        [CALayer addCustomValueForUndefinedKeyImplementation: (IMP)UnknownExceptionKeyIMP];
    });
}

添加之后，如果項(xiàng)目中再使用一些非法的valueForKey或setValue:forKey:方法時(shí)，不至于崩潰閃退,從而可以避免一些系統(tǒng)NSUnknownException類型的報(bào)錯(cuò)。如下例子：

//不可變字典 進(jìn)行setValue:ForKey:操作
    NSDictionary *dict = [NSDictionary dictionary];
    [dict setValue:@"heqican" forKey:@"name"];

//不可變數(shù)組進(jìn)行setValue:forKey:操作
    NSArray *array = @[@"1",@"2"];
    [array setValue:@"松小寶" forKey:@"name"];