我想写一个计时器类来记录函数的平均运行时间。所以我想保存函数的运行次数。但是字典中的项目不会更改。
这是我的代码:
@implementation Timer {
NSDate *startTime;
// NSString *item;
NSMutableDictionary *itemCounts;
NSMutableDictionary *itemTimes;
}
- (void)tic {
startTime = [NSDate date];
}
- (void)tocWithMessage:(NSString*)message {
if (itemCounts[message] == nil) {
// itemCounts[message] = @1;
[itemCounts setValue:@1 forKey:message];
NSLog(@"%d", [itemCounts[message] integerValue]);
} else {
itemCounts[message] = @([itemCounts[message] integerValue] + 1);
}
double totalTime = [itemTimes[message] doubleValue];
double thisTime = -[startTime timeIntervalSinceNow] * 1000;
totalTime += thisTime;
itemTimes[message] = @(totalTime);
int count = [itemCounts[message] integerValue];
double averageTime = totalTime / count;
NSLog(@"%@: No.%d, average time: %lfms", message, count, averageTime);
// std::cout << message << ": " << 1. * (clock() - timerTimestamp) / CLOCKS_PER_SEC * 1000 << "ms" << std::endl;
}
@end
但是 itemCounts[message] 总是为零。请帮我:)
提前感谢!
你忘了初始化字典。在 Swift 中,如果你这样做,你会看到崩溃:)
你只声明了字典。
在使用它们之前,您必须在某处初始化它们:
itemCounts = [[NSMutableDictionary alloc] init];
itemTimes = [[NSMutableDictionary alloc] init];