iOS一些小技巧

搜集了网上一些常用的开发小技巧，集中到一起看－，－

1 TableView下面的那些cell的空显示

self.tableView.tableFooterView = [[UIView alloc] init]

2 ScrollView莫名其妙不能在viewController划到顶怎么办？也就是修正导航栏

self.automaticallyAdjustsScrollViewInsets = NO;

3 键盘事件？
使用IQKeyboardManager（GitHub上可搜索）

4 控件的局部圆角问题
你是不是也遇到过这样的问题，一个button或者label，只要右边的两个角圆角，或者只要一个圆角。该怎么办呢。这就需要图层蒙版来帮助我们了

    CGRect rect = CGRectMake(0, 0, 100, 50);
    CGSize radio = CGSizeMake(5, 5);//圆角尺寸
    UIRectCorner corner = UIRectCornerTopLeft|UIRectCornerTopRight;//这只圆角位置
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corner cornerRadii:radio];
    CAShapeLayer *masklayer = [[CAShapeLayer alloc]init];//创建shapelayer
    masklayer.frame = button.bounds;
    masklayer.path = path.CGPath;//设置路径
    button.layer.mask = masklayer;

5 navigationBar的透明问题
如果仅仅把navigationBar的alpha设为0的话，那就相当于把navigationBar给隐藏了，大家都知道，父视图的alpha设置为0的话，那么子视图全都会透明的。那么相应的navigationBar的标题和左右两个按钮都会消失。这样显然达不到我们要求的效果。
（1）如果仅仅是想要navigationBar透明，按钮和标题都在可以使用以下方法：

 [self.navigationController.navigationBar setBackgroundImage:[UIImage new] 
forBarMetrics:UIBarMetricsDefault];//给navigationBar设置一个空的背景图片即可实现透明，而且标题按钮都在

5 调用代码使APP进入后台，达到点击Home键的效果。

    [[UIApplication sharedApplication] performSelector:@selector(suspend)];

6 获取UIWebView的高度

- (void)webViewDidFinishLoad:(UIWebView *)webView {
  CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight;"] intValue];
  if (self.webViewHeight != height && self.count <= 3) {
    self.webViewHeight = height;
    self.count++;
    
    [self updateUI];
  }
}
 
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
  self.webViewHeight = webView.scrollView.contentSize.height;
  return YES;
}

7 带有中文的URL处理

http://static.tripbe.com/videofiles/视频/我的自拍视频.mp4
NSString *path  = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL,                                                                                                             (__bridge CFStringRef)model.mp4_url,                                                                                                        CFSTR(""),                                                                                                                CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));

8 禁止程序运行时自动锁屏

[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

9 用十六进制获取UIColor

+ (UIColor *)colorWithHexString:(NSString *)color
{
    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

    // String should be 6 or 8 characters
    if ([cString length] < 6) {
        return [UIColor clearColor];
    }

    // strip 0X if it appears
    if ([cString hasPrefix:@"0X"])
        cString = [cString substringFromIndex:2];
    if ([cString hasPrefix:@"#"])
        cString = [cString substringFromIndex:1];
    if ([cString length] != 6)
        return [UIColor clearColor];

    // Separate into r, g, b substrings
    NSRange range;
    range.location = 0;
    range.length = 2;

    //r
    NSString *rString = [cString substringWithRange:range];

    //g
    range.location = 2;
    NSString *gString = [cString substringWithRange:range];

    //b
    range.location = 4;
    NSString *bString = [cString substringWithRange:range];

    // Scan values
    unsigned int r, g, b;
    [[NSScanner scannerWithString:rString] scanHexInt:&r];
    [[NSScanner scannerWithString:gString] scanHexInt:&g];
    [[NSScanner scannerWithString:bString] scanHexInt:&b];

    return [UIColor colorWithRed:((float) r / 255.0f) green:((float) g / 255.0f) blue:((float) b / 255.0f) alpha:1.0f];
}