1. ForLoop
, For - in
, enumerateObjects
这个三个方法的区别:
遍历一个数组用For-in最快.
通过Value查询index的时候, 面对大量的数组推荐使用 enumerateObjectsWithOptions
的并行方法.
遍历字典类型的时候, enumerateKeysAndObjectsUsingBlock效率最高
1.1遍历数组
NSMutableArray *test = [NSMutableArray array];
for (int i = ; i < ; i ++) {
[test addObject:@(i)];
} //ForLoop方法
__block int sum = ;
double date_s = CFAbsoluteTimeGetCurrent();
for (int i = ; i < test.count; i ++) {
sum += [test[i] integerValue];
}
double date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"Sum : %d ForLoop Time: %f ms",sum,date_current * ); //For - in方法
sum = ;
date_s = CFAbsoluteTimeGetCurrent();
for (NSNumber *num in test) {
sum += [num integerValue];
}
date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"Sum : %d For-in Time: %f ms",sum,date_current * ); //enumerateObjectsUsingBlock方法
sum = ;
date_s = CFAbsoluteTimeGetCurrent();
[test enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
sum += [obj integerValue];
}];
date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"Sum : %d enumrateBlock Time: %f ms",sum,date_current * );
打印如下:
总结:遍历一个数组用For-in最快.
1.2-通过Value查找Index看谁快
实验:For - in
, enumerateObjectsUsingBlock
, enumerateObjectsWithOptions
这个三个方法: (ForLoop已经不再继续讨论了)
NSMutableArray *test = [NSMutableArray array];
for (int i = ; i < ; i ++) {
[test addObject:@(i + )];
} //For-in
__block NSInteger index = ;
double date_s = CFAbsoluteTimeGetCurrent();
for (NSNumber *num in test) {
if ([num integerValue] == ) {
index = [test indexOfObject:num];
break;
}
}
double date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"index : %ld For-in Time: %f ms",(long)index,date_current * ); //enumerateObjectsUsingBlock
index = ;
date_s = CFAbsoluteTimeGetCurrent();
[test enumerateObjectsUsingBlock:^(id num, NSUInteger idx, BOOL *stop) {
if ([num integerValue] == ) {
index = idx;
*stop = YES;
}
}];
date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"index : %ld enumerateBlock Time: %f ms",(long)index,date_current * ); //enumerateObjectsWithOptions
index = ;
date_s = CFAbsoluteTimeGetCurrent();
[test enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id num, NSUInteger idx, BOOL *stop) {
if ([num integerValue] == ) {
index = idx;
*stop = YES;
}
}];
date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"index : %ld enumerateObjectsWithOptions Time: %f ms",(long)index,date_current * );
打印:
结论:通过Value查询index的时候, 面对大量的数组推荐使用 enumerateObjectsWithOptions
的并行方法.
1.3遍历字典
这里我们比较一下使用 For-in
和 enumerateKeysAndObjectsUsingBlock
这个两个方法:
NSDictionary *testDictionary = @{
@"Auther" : @"yyyyy",
@"Game" : @"Dota",
@"App" : @"dddddd",
@"Market" : @"AppStore"
}; NSMutableArray *forInArry1 = [NSMutableArray array];
NSMutableArray *forInArry2 = [NSMutableArray array];
NSMutableArray *enumArry = [NSMutableArray array]; //For - in方法 直接allValues
double date_s = CFAbsoluteTimeGetCurrent();
NSArray *values = testDictionary.allValues;
for (NSString *value in values) {
[forInArry1 addObject:value];
}
double date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"index : %ld For-in-forInArry1 Time: %f ms",(long)index,date_current * ); //For - in方法,+根据key取value值
date_s = CFAbsoluteTimeGetCurrent();
NSArray *keys = testDictionary.allKeys;
for (NSString *key in keys) {
NSString *Value = testDictionary[key];
[forInArry2 addObject:Value];
}
date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"index : %ld For-in-forInArry2 Time: %f ms",(long)index,date_current * ); //enumerateKeysAndObjectsUsingBlock方法.
date_s = CFAbsoluteTimeGetCurrent();
[testDictionary enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
[enumArry addObject:obj];
}];
date_current = CFAbsoluteTimeGetCurrent() - date_s;
NSLog(@"index : %ld enumerateKeysAndObjectsUsingBlock Time: %f ms",(long)index,date_current * );
打印:
结论:遍历字典类型的时候, enumerateKeysAndObjectsUsingBlock效率最高