转载，忘记出处了...
- 将 view 的所有子视图移除
// 用 makeObjectsPerformSelector
[view.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
- 数组的二分法查找, 时间复杂度是 O(log n)
NSArray *arr = @[@"21", @"12", @"13", @"14", @"25", @"26", @"27", @"28", @"29"];
NSInteger index = [arr indexOfObject:@"14"
inSortedRange:NSMakeRange(0, [arr count])
options:NSBinarySearchingFirstEqual
usingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {
if ([obj1 integerValue] > [obj2 integerValue]) {
return NSOrderedDescending;
}else if ([obj1 integerValue] < [obj2 integerValue]) {
return NSOrderedAscending;
}
return NSOrderedSame;
}];
NSLog(@"index = %ld", index);
- 使用 NSAttributedString 设置不同大小字体时, 使两种字体都垂直居中, 其中 a 是大号字体, b 是小号字体
[mark addAttribute:NSBaselineOffsetAttributeName value:@(0.36 * (a - b)) range:NSMakeRange(0, name.length)];
- 老项目没有进行字体适配，导致有些文本在 iPhone5 机型上无法显示完整，这里写了一个 UIFont 的分类，用 runtime 对 UIFont 的
systemFontOfSize:方法进行了替换，几行代码基本上搞定了老项目存在的问题；
#import "UIFont+NNSize.h"
#import <objc/runtime.h>
@implementation UIFont (NNSize)
+ (void)load {
Method newMethod = class_getClassMethod([self class], @selector(nnCustomSystemFontOfSize:));
Method method = class_getClassMethod([self class], @selector(systemFontOfSize:));
method_exchangeImplementations(newMethod, method);
}
+ (UIFont *)nnCustomSystemFontOfSize:(CGFloat)fontSize {
UIFont *newFont = nil;
if ([[UIScreen mainScreen] bounds].size.height < 667.0) {
newFont = [UIFont nnCustomSystemFontOfSize:fontSize * 0.9];
} else {
newFont = [UIFont nnCustomSystemFontOfSize:fontSize];
}
return newFont;
}
@end
- 隐藏导航栏下边的灰色线条，直接在自定义的 UINavigationController 类里调用下边的方法
- (UIImageView *)findHairlineImageViewUnder:(UIView *)view {
if ([view isKindOfClass:UIImageView.class] && view.bounds.size.height <= 1.0) {
return (UIImageView *)view;
}
for (UIView *subview in view.subviews) {
UIImageView *imageView = [self findHairlineImageViewUnder:subview];
if (imageView) {
return imageView;
}
}
return nil;
}
比如：[self findHairlineImageViewUnder:self.navigationBar].hidden = YES;
- 动态修改状态栏的颜色
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
self.offset = scrollView.contentOffset.y;
[self setNeedsStatusBarAppearanceUpdate];
}
- (UIStatusBarStyle)preferredStatusBarStyle {
if (self.offset <= -200) {
return UIStatusBarStyleDefault;
}
return UIStatusBarStyleLightContent;
}
- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
return UIStatusBarAnimationFade;
}
- 监听界面滚动，淡入淡出更改电池条颜色
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
[self setNeedsStatusBarAppearanceUpdate];
}
- (UIStatusBarStyle)preferredStatusBarStyle {
if (self.collectionView.contentOffset.y <= -200) {
return UIStatusBarStyleLightContent;
}
return UIStatusBarStyleDefault;
}
- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
return UIStatusBarAnimationFade;
}
- 判断控件是不是指定视图的子视图
BOOL isView = [textView isDescendantOfView:self.view];
- 修改 UITextField 中 Placeholder 的文字颜色
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
- 防止 UIScrollView 手势覆盖侧滑手势
[scrollView.panGestureRecognizer requireGestureRecognizerToFail:self.navigationController.interactivePopGestureRecognizer];
