iOS-NSDictionaryOfVariableBindings自动去除字典空值对象

野性酷女 2023-10-18 22:42 112阅读 0赞

模仿系统的快速生成字典的方法NSDictionaryOfVariableBindings,并过滤掉值为`nil`的对象或内容全为空格字符串,防止字典crash。

推荐适用场合：网络请求生成参数字典，无需判空。  
其他创建字典的地方也可以使用，注意此方法会过滤掉全为空格及`@""`字符串，如不需要可自行修改。

创建分类文件NSDictionary+Safe

NSDictionary+Safe.m 中代码如下：

#define BZDictionaryOfVariableBindings(...) [NSDictionary _BZDictionaryOfVariableBindings:@"" # __VA_ARGS__, __VA_ARGS__]
    
    
    @interface NSDictionary (Safe)
    
    /**
     安全获取value值
     
     @param aKey <#aKey description#>
     @return <#return value description#>
     */
    - (id)objectForKeyCheck:(id)aKey;
    
    /**
     模仿系统的对象生成字典的宏定义：NSDictionaryOfVariableBindings(...)
     if v1 = @"something"; v2 = nil; v3 = @"something"; v4 = @"";
     ZXDictionaryOfVariableBindings(v1, v2, v3) is equivalent to [NSDictionary dictionaryWithObjectsAndKeys:v1, @"v1", v3, @"v3", nil];
     并且参数的值可为nil,@"", 会自动去除值为nil, @"", @"  "等的对象
     */
    + (NSDictionary *)_BZDictionaryOfVariableBindings:(NSString *)firstArg, ...;

NSDictionary+Safe.h 中代码如下：

#import "NSDictionary+Safe.h"
    
    @implementation NSDictionary (Safe)
    
    - (id)objectForKeyCheck:(id)aKey{
        if ([self.allKeys containsObject:aKey]) {
            return [self objectForKey:aKey];
        }
        NSLog(@"%@", [NSThread callStackSymbols]);
        return nil;
    }
    
    + (NSDictionary *)_BZDictionaryOfVariableBindings:(NSString *)firstArg, ... {
        firstArg = [firstArg stringByReplacingOccurrencesOfString:@" " withString:@""];
        NSArray *keys = [firstArg componentsSeparatedByString:@","];
        NSMutableDictionary *dic = [NSMutableDictionary dictionaryWithCapacity:keys.count];
        va_list list;
        if (firstArg) {
            va_start(list, firstArg);
            id arg;
            for (NSString *key in keys) {
                arg = va_arg(list, id);
                if (!arg || [arg isKindOfClass:[NSNull class]]) {
                    continue;
                }
                if ([arg isKindOfClass:[NSString class]]) {
                    if ([[arg stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] length] != 0) {
                        [dic setObject:arg forKey:key];
                    }
                } else {
                    [dic setObject:arg forKey:key];
                }
            }
            va_end(list);
        }
        return dic;
    }

拿到后台返回字段，普通的字典添加元素，会crash掉

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