ios 杂记

1. makeObjectsPerformSelector

- (void)makeObjectsPerformSelector:(SEL)aSelector;

- (void)makeObjectsPerformSelector:(SEL)aSelector withObject:(id)argument;

 

这是 NSArray和NSSet的两个方法，相信大家很少用，它类似于 for循环，但有效率高于for循环

makeObjectsPerformSelector:类似于NSNotifation机制，并发的执行同一件事，不能像for循环那样区别对待

所以参数 argument 必须是非基本类型 ，如果要是用基本类型 请转换程 NSNumber 或者NSValue

 

[_leavesLayers makeObjectsPerformSelector:@selector(removeFromSuperlayer)];

2. enumerateObjectsUsingBlock

NSArray *myArray = // 获取数组
[myArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
    if ([(NSString *)obj isEqualToString:@"Cupertino"]) {
        NSLog(@”We’re near the mothership!”);
        *stop = YES;
    }
}];

3. UIGestureRecognizer

http://www.cnblogs.com/pengyingh/articles/2379479.html

4. dateFromComponents

为什么dateFromComponents显示日期与实际日期有差别，貌似少了一天？
是因为没有设置TimeZone,
[self.calendar setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"GMT"]];

5. ios根据设备动态加载

if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
　　//如果是iphone
}else
{
　　//
}