1、GCD线程间的通信
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_queue_t mainQueue = dispatch_get_main_queue();
dispatch_async(queue, ^{
//这里是延时操作方法
dispatch_async(mainQueue, ^{
//刷新UI
});
});
2、iOS 11之后上拉刷新TableView cell乱跳问题
只需加下面三行代码即可。
estimatedRowHeight是一个预估高度，iOS11之前是为0，在iOS11下，这个值默认为44。
我们知道tableView是继承于ScrollView的，一个scrollView能滑动，需要设置contentSize，那么tableView的contentSize怎么来呢？iOS11之前，会调用tableView每一个cell的heightForRowAtIndexPath来算出整个高度，从而相加得出contentSize来，这一个步骤挺耗性能！
所以iOS11，默认打开了estimatedRowHeight估算高度功能，当tableView创建完成后，contentSize为estimatedRowHeight（默认值为44）*cell的数量，不需要遍历每一个cell的heightForRowAtIndexPath来计算了。
_tableView.estimatedRowHeight = 0;
_tableView.estimatedSectionHeaderHeight = 0;
_tableView.estimatedSectionFooterHeight = 0;
3、多个异步请求都结束后在刷新界面数据
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_async(group, queue, ^{
[self requestCycleData];
});
dispatch_group_async(group, queue, ^{
[self heartTextRequest];
});
dispatch_group_async(group, queue, ^{
[self recommendArticleImageRequest];
});
dispatch_group_async(group, queue, ^{
[self articleListRequestWithPageNo:0 andPageSize:10];
});
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
//刷新数据
});
}
requestCycleData
-(void)requestCycleData{
dispatch_semaphore_t sem = dispatch_semaphore_create(0);
[MMDHomeOrderRequest homeTopImageRequestWithBlock:^(MMDResponse *response) {
dispatch_semaphore_signal(sem);
}];
dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);
}
4、Label字符串设置不同颜色
根据位置修改颜色
NSMutableAttributedString *string = [[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@"剩余%@分%@秒自动失效",str_minute,str_second]];
[string addAttribute:NSForegroundColorAttributeName value:UIColor_Blue range:NSMakeRange(2,2)];
[string addAttribute:NSForegroundColorAttributeName value:UIColor_Blue range:NSMakeRange(5,2)];
self.timeLeftToPayLabel.attributedText = string;
根据字符串匹配修改颜色
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:format_time];
NSRange range11 = [[str string] rangeOfString:[NSString stringWithFormat:@"%@分%@秒",str_minute,str_second]];
[str addAttribute:NSForegroundColorAttributeName value:UIColor_Blue range:range11];
NSRange range22 = [[str string] rangeOfString:@"剩余自动失效"];
[str addAttribute:NSForegroundColorAttributeName value:UIColor_Text range:range22];
self.timeLeftToPayLabel.attributedText = str;
5、获取当前Window的controller视图
- (UIViewController *)topViewController {
UIViewController *resultVC;
resultVC = [self _topViewController:[[UIApplication sharedApplication].keyWindow rootViewController]];
while (resultVC.presentedViewController) {
resultVC = [self _topViewController:resultVC.presentedViewController];
}
return resultVC;
}
- (UIViewController *)_topViewController:(UIViewController *)vc {
if ([vc isKindOfClass:[UINavigationController class]]) {
return [self _topViewController:[(UINavigationController *)vc topViewController]];
} else if ([vc isKindOfClass:[UITabBarController class]]) {
return [self _topViewController:[(UITabBarController *)vc selectedViewController]];
} else {
return vc;
}
return nil;
}
6、UIPageControl使用自定义图片间距设置
继承UIPageControl重写layoutSubviews和setCurrentPage方法
#import "MMDPageControl.h"
@implementation MMDPageControl
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// Drawing code
}
*/
#define margin 8
#define dotNormalW 8
#define dotCurrentW 16
- (void)layoutSubviews
{
[super layoutSubviews];
//计算整个pageControll的宽度
CGFloat newW = (self.subviews.count - 1) * (dotNormalW + margin) + dotCurrentW;
//设置新frame
self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, newW, self.frame.size.height);
//设置居中
CGPoint center = self.center;
center.x = self.superview.center.x;
self.center = center;
for (NSUInteger subviewIndex = 0; subviewIndex < [self.subviews count]; subviewIndex++) {
UIImageView* subview = [self.subviews objectAtIndex:subviewIndex];
CGSize size;
if (subviewIndex == self.currentPage) {
size.height = 2;
size.width = dotCurrentW;
[subview setFrame:CGRectMake(subviewIndex * (dotNormalW + margin), subview.frame.origin.y, size.width,size.height)];
} else {
size.height = 2;
size.width = dotNormalW;
if (subviewIndex > self.currentPage) {
[subview setFrame:CGRectMake(dotCurrentW + (margin * subviewIndex) + (subviewIndex - 1) * dotNormalW, subview.frame.origin.y, size.width,size.height)];
}else{
[subview setFrame:CGRectMake(subviewIndex * (dotNormalW + margin), subview.frame.origin.y, size.width,size.height)];
}
}
}
}
-(void)setCurrentPage:(NSInteger)currentPage{
[super setCurrentPage:currentPage];
for (NSUInteger subviewIndex = 0; subviewIndex < [self.subviews count]; subviewIndex++) {
UIImageView* subview = [self.subviews objectAtIndex:subviewIndex];
CGSize size;
if (subviewIndex == currentPage) {
size.height = 2;
size.width = dotCurrentW;
[subview setFrame:CGRectMake(subviewIndex * (dotNormalW + margin), subview.frame.origin.y, size.width,size.height)];
} else {
size.height = 2;
size.width = dotNormalW;
if (subviewIndex > currentPage) {
[subview setFrame:CGRectMake(dotCurrentW + (margin * subviewIndex) + (subviewIndex - 1) * dotNormalW, subview.frame.origin.y, size.width,size.height)];
}else{
[subview setFrame:CGRectMake(subviewIndex * (dotNormalW + margin), subview.frame.origin.y, size.width,size.height)];
}
}
}
}
@end
7、数组循环遍历 数据筛选 出错写法
for (int i = 0; i < array.count; i++) {
NSDictionary *dic = [NSDictionary dictionaryWithDictionary:array[i]];
if ([dic hl_integerForkey:@"displayPosition"] == 0) {
[array removeObject:dic];
}
}
数组在遍历过程中只能修改、不能进行删除操作、切记这种错误的写法，不知道你这样写过没