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

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/