@encode关键字

@encode()

为了更好的互操作性，Objective-C 的数据类型，甚至自定义类型、函数或方法的元类型，都可以使用 ASCII 编码。@encode(aType) 可以返回该类型的 C 字符串（char *）的表示

    NSDictionary *dic = @{@"key1":[NSNumber numberWithBool:YES],
                          @"key2":[NSNumber numberWithDouble:77.777777f],
                          @"key3":[NSNumber numberWithInt:99],
                          @"key4":[NSNumber numberWithFloat:55.0f],
                          @"key5":[NSNumber numberWithUnsignedInteger:100]};
    for(NSString *key in dic){
        id value = [dic valueForKey:key];
        NSLog(@"value === %@",value);
        if([value isKindOfClass:[NSNumber class]]){
            const char * pObjCType = [((NSNumber*)value) objCType];
            if (strcmp(pObjCType, @encode(int))  == 0) {
                NSLog(@"字典中key=%@的值是int类型,值为%d",key,[value intValue]);
            }
            if (strcmp(pObjCType, @encode(float)) == 0) {
                NSLog(@"字典中key=%@的值是float类型,值为%f",key,[value floatValue]);
            }
            if (strcmp(pObjCType, @encode(double))  == 0) {
                NSLog(@"字典中key=%@的值是double类型,值为%f",key,[value doubleValue]);
            }
            if (strcmp(pObjCType, @encode(_Bool)) == 0 || strcmp([value objCType], @encode(char)) == 0) {
                NSLog(@"字典中key=%@的值是bool类型,值为%i",key,[value boolValue]);
            }
            if (strcmp(pObjCType, @encode(NSUInteger)) == 0 || strcmp(pObjCType, @encode(NSInteger)) == 0) {
                NSLog(@"字典中key=%@的值是NSUInteger类型,值为%i",key,[value boolValue]);
            }
        }    }    /*
     2014-03-26 10:26:49.259 Test[88121:60b] value === 99
     2014-03-26 10:26:49.260 Test[88121:60b] 字典中key=key3的值是int类型,值为99
     2014-03-26 10:26:49.260 Test[88121:60b] value === 1
     2014-03-26 10:26:49.261 Test[88121:60b] 字典中key=key1的值是bool类型,值为1
     2014-03-26 10:26:49.261 Test[88121:60b] value === 55
     2014-03-26 10:26:49.261 Test[88121:60b] 字典中key=key4的值是float类型,值为55.000000
     2014-03-26 10:26:49.262 Test[88121:60b] value === 77.77777862548828
     2014-03-26 10:26:49.262 Test[88121:60b] 字典中key=key2的值是double类型,值为77.777779
     2014-03-26 10:26:49.262 Test[88121:60b] value === 100
     2014-03-26 10:26:49.262 Test[88121:60b] 字典中key=key5的值是NSUInteger类型,值为1
     2014-03-26 10:26:49.263 Test[88121:60b] EOCStringConstant =  EOCStringConstant
     */

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