随着第三方框架AFNetworking的兴起,越来越多的人开始使用AFNetworking来调用接口,发送请求.
而在需要请求体的请求中,一般都是使用字典来作为请求体.
字典的初始化有很多种,本人较为常用的是以下这种:

NSDictionary *params = @{ @"key1":value1 ,@"key2":value2};

但是,value的值一般都是动态传入的,所以有存在nil的可能,结果就是你懂的↓

*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]
: attempt to insert nil object from objects[0]'**

那么就有人会说,你应该在传入前判断value是否为nil,或者使用较为安全的方法,如:

[NSDictionary dictionaryWithObjectsAndKeys:[self backString: value],@"key", nil];

 -(NSString *)backString:(NSString *)string
{
if ([string isEqual:[NSNull null]]) {
    return @"";
} else {
    return string;
}
}

是的,这些方法都可以解决上面存在的问题,但是我懒,懒得写那么多.
所以就决定是你了,去吧,runtime! [手动滑稽],一个.m文件搞定问题

    #import <Foundation/Foundation.h>
    #import <objc/message.h>
    @implementation NSDictionary (Swizzle)
    + (void)load { 
    static dispatch_once_t onceToken; 
    dispatch_once(&onceToken, ^{                         
    [objc_getClass("__NSPlaceholderDictionary") 
    swizzleSelector:@selector(initWithObjects:forKeys:count:) withSwizzledSelector:@selector(safeInitWithObjects:forKeys:count:)]; });}
    - (instancetype)safeInitWithObjects:(const id _Nonnull __unsafe_unretained *)objects forKeys:(const id _Nonnull __unsafe_unretained *)keys count:(NSUInteger)cnt { 
    BOOL containNilObject = NO; 
    for (NSUInteger i = 0; i < cnt; i++) {
     if (objects[i] == nil) { 
    containNilObject = YES; 
    NSLog(@"reason: ***object cannot be nil (key: %@)", keys[i]); 
    } 
    } if (containNilObject) { 
    NSUInteger nilCount = 0;
     for (NSUInteger i = 0; i < cnt; ++i) {
     if (objects[i] == nil) { 
    nilCount ++; 
    } 
    } 
    NSUInteger length = cnt - nilCount;
     if (length > 0) { NSUInteger index = 0; 
    id __unsafe_unretained newObjects[length]; 
    id __unsafe_unretained newKeys[length];
     for (NSUInteger i = 0; i < cnt; ++i) { 
    if (objects[i] != nil) { 
    newObjects[index] = objects[i];
     newKeys[index] = keys[i];
     index ++ ; 
    }
     }
     NSLog(@"fixedDictionary:%@",[self safeInitWithObjects:newObjects forKeys:newKeys count:length]);
     return [self safeInitWithObjects:newObjects forKeys:newKeys count:length];
     }         
    } return [self safeInitWithObjects:objects forKeys:keys count:cnt];
    }
    + (void)swizzleSelector:(SEL)originalSelector withSwizzledSelector:(SEL)swizzledSelector {
     Class class = [self class]; 
    Method originalMethod = class_getInstanceMethod(class, originalSelector); 
    Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector); 
    BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
     if (didAddMethod) { 
    class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod)); 
    } else {
     method_exchangeImplementations(originalMethod, swizzledMethod); 
    }
    }
    @end