iOS小知识点集锦

---

title: iOS小知识点集锦
date: 2017-06-01 15:28:57
categories: "iOS"
tags:

• Objective-C
  description: 自己记录的小知识点

---

• UIView 视频全屏 masonry 约束设置

    UIView *player = [[UIView alloc] init];
    [self.view addSubview:player];
    
    CGFloat wid = [UIScreen mainScreen].bounds.size.width;
    CGFloat hei = [UIScreen mainScreen].bounds.size.height;
    CGFloat rate = wid < hei ? (wid/hei) : (hei/wid);
    [player mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self.view);
        make.left.right.equalTo(self.view);
        make.height.mas_equalTo(player.mas_width).multipliedBy(rate);
    }];

• Masonry实现动画更新约束

// 告诉self.view约束需要更新
[self.view setNeedsUpdateConstraints];
// 调用此方法告诉self.view检测是否需要更新约束，若需要则更新，下面添加动画效果才起作用
[self.view updateConstraintsIfNeeded];

[UIView animateWithDuration:0.3 animations:^{
  [self.view layoutIfNeeded];
}];

• UISlider更改进度条的粗细 、修改圆点位置

//需要重写UISlider的trackRectForBounds 方法
- (CGRect)trackRectForBounds:(CGRect)bounds {
    bounds.origin.y = bounds.size.height / 2.0 - 2;
    bounds.size.height = 4;
    return bounds;
}

//小圆点Rect修改
- (CGRect)thumbRectForBounds:(CGRect)bounds trackRect:(CGRect)rect value:(float)value
{
    rect.origin.x = rect.origin.x - 3 ;
    rect.size.width = rect.size.width +6;
    return [super thumbRectForBounds:bounds trackRect:rect value:value];
}

• iOS获取View所在的控制器、导航控制器

//获取控制器
- (UIViewController*)viewController {
    for (UIView* next = [self superview]; next; next = next.superview) {
        UIResponder* nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UINavigationController class]]) {
            return (UIViewController*)nextResponder;
        }
    }
    return nil;
}

//获取导航控制器
- (UINavigationController*)navigationController {
    for (UIView* next = [self superview]; next; next = next.superview) {
        UIResponder* nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UINavigationController class]]) {
            return (UINavigationController*)nextResponder;
        }
    }
    return nil;
}

• UILabel 设置行间距

- (NSAttributedString *)getParagraphText:(NSString*)text LineSpacing:(CGFloat)spacing{
    if(text == nil || text.length == 0){
        return nil;
    }
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc]initWithString:text];;
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];
    [paragraphStyle setLineSpacing:spacing];
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, text.length)];
    return attributedString;
}

//使用
self.titleLabel.attributedText = [self getParagraphText:infModel.title LineSpacing:7];

• UIView获取父控制器／父导航控制器

//创建UIView的分类
//获取当前控制器
- (UIViewController *)getCurrentVC {
    UIResponder *next = self.nextResponder;
    do {
        //判断响应者是否为视图控制器
        if ([next isKindOfClass:[UIViewController class]]) {
            return (UIViewController *)next;
        }
        next = next.nextResponder;
        
    } while (next != nil);
    return nil;
}

//获取导航控制器
- (UINavigationController *)getCurrentNavVC {
    UIResponder *next = self.nextResponder;
    do {
        //判断响应者是否为视图控制器
        if ([next isKindOfClass:[UINavigationController class]]) {
            return (UINavigationController *)next;
        }
        next = next.nextResponder;
        
    } while (next != nil);
    return nil;
}

• 拉伸图片

//拉伸图片
+ (UIImage *)resizedImageWithName:(NSString *)name
{
    return [self resizedImageWithName:name left:0.5 top:0.5];
}

+ (UIImage *)resizedImageWithName:(NSString *)name left:(CGFloat)left top:(CGFloat)top
{
    UIImage *image = [UIImage imageNamed:name];
    return [image stretchableImageWithLeftCapWidth:image.size.width * left topCapHeight:image.size.height * top];
}

• **判断当前控制器是push 还是present **

//方法一
- (IBAction)dismiss:(id)sender {
    if (self.presentingViewController) {
        [self dismissViewControllerAnimated:YES completion:nil];
    } else {
        [self.navigationController popViewControllerAnimated:YES];
    }
}

//方法二
- (IBAction)dismiss:(id)sender {
    if (self.navigationController.topViewController == self) {
        [self.navigationController popViewControllerAnimated:YES];
    } else {
        [self dismissViewControllerAnimated:YES completion:nil];
    }
}

原文地址： http://oxy.pub