Objective-C中3种枚举比较及KVC两个小技巧

Objective-C中3种枚举比较及KVO两个小技巧

一：oc的3种枚举

• for循环
• for in
• 枚举块

   如代码

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NSUInteger totalCount = 10000; NSMutableArray *array = [NSMutableArray arrayWithCapacity:totalCount];     //create an array including 10000 elements for (int i = 0; i<totalCount; i++) {     array[i] = [@(i) stringValue]; }     //C Language For Loop Enumeration CFTimeInterval start1 = CACurrentMediaTime(); for (int j = 0; j< totalCount; j++) {     NSLog(@"%@",array[j]); } CFTimeInterval end1 = CACurrentMediaTime(); NSLog(@"C Language For Loop method %f",end1 - start1);     //Objective-C Fast Enumeration CFTimeInterval start2 = CACurrentMediaTime(); for (NSString *string in array) {     NSLog(@"%@",string); } CFTimeInterval end2 = CACurrentMediaTime(); NSLog(@"Objective-C Fast Enumeration method %f",end2 - start2);     //Objective-C Block Enumeration CFTimeInterval start3 = CACurrentMediaTime(); [array enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(NSString * obj, NSUInteger idx, BOOL *stop) {     NSLog(@"%@",obj); }]; CFTimeInterval end3 = CACurrentMediaTime(); NSLog(@"Objective-C Block Enumeration method %f",end3 - start3);

　　

 打印结果：

综上：块是最快的！

二：kvc两个小技巧

    1:keyPath取嵌套字典的值；

    2: kvc消息的高级传递

 

转自：http://nijino.cn/blog/2013/07/02/using-kvc/

       http://nijino.cn/blog/2014/03/11/comparison-for-3-enumeration-methods-in-objective-c/