IOS开发基础知识--碎片4

十七:返回到主线程进行操作,对UI进行更新只能在主线程进行

 /*将数据显示到UI控件,注意只能在主线程中更新UI,
     另外performSelectorOnMainThread方法是NSObject的分类方法，每个NSObject对象都有此方法，
     它调用的selector方法是当前调用控件的方法，例如使用UIImageView调用的时候selector就是UIImageView的方法
     Object：代表调用方法的参数,不过只能传递一个参数(如果有多个参数请使用对象进行封装)
     waitUntilDone:是否线程任务完成执行
 */

[self performSelectorOnMainThread:@selector(updateImage:) withObject:data waitUntilDone:YES];

十八:UIImageView用法总结

//初始化
UIImageView  *imageView=[[UIImageView alloc] initWithFrame:CGRectMake(, , , )];

//需要设置图片 UIImage(第一种跟第二种会Cache到内存,消耗内存,但以后访问有优势,当只加载一次推荐用第三种)

第一种：[imageView setImage:[UIImage imageNamed:@"1.jpeg"]];

//第二种：
NSString *filePath=[[NSBundle mainBundle] pathForResource:@"" ofType:@"jpeg"];
UIImage *images=[UIImage imageWithContentsOfFile:filePath];
//[imageView setImage:images]; 

//第三种：
NSData *data=[NSData dataWithContentsOfFile:filePath];
UIImage *image2=[UIImage imageWithData:data];
[imageView setImage:image2];

十九:通过tag获得子控件

首先要把这个子控件的属性增加一个tag,

    UIButton* button= [UIButton buttonWithType:UIButtonTypeCustom];
    button.tag=;
    button.frame=CGRectMake(, , , );
    [button addTarget:self action:@selector(play:) forControlEvents:UIControlEventTouchUpInside];
    [button setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateNormal];
    [self.view addSubview:button];

然后再可以通过viewWithTag去获得,self.view是本视图,是Button的父视图

    UIButton * button = (UIButton*)[self.view viewWithTag:];

二十:动态修改按键的背景图

带一个参数,play:,就可以通过这个方法进行操作

    //播放按钮
    UIButton* button= [UIButton buttonWithType:UIButtonTypeCustom];
    button.tag=;
    button.frame=CGRectMake(, , , );
    [button addTarget:self action:@selector(play:) forControlEvents:UIControlEventTouchUpInside];
    [button setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateNormal];
    [self.view addSubview:button];

//播放
-(void)play:(UIButton*)button
{
    if(_audioPlayer.playing)
    {
        [button setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateNormal];
        [_audioPlayer pause];
    }
    else
    {
        [button setImage:[UIImage imageNamed:@"stop.png"] forState:UIControlStateNormal];
        [_audioPlayer play];
    }

}

二十一:判断是不是模拟机

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.title=@"判断是否是模拟机";
    [self isSimulator];
}

-(void)isSimulator
{
    if (TARGET_IPHONE_SIMULATOR) {
        NSLog(@"是模拟机");
    }else{
        NSLog(@"不是模拟机");
    }

}

二十二:16进制色彩转化成UIColor

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    UIView *view=[[UIView alloc]initWithFrame:CGRectMake(, , , )];
    view.backgroundColor=[self colorWithHexString:@"e26562"];
    [self.view addSubview:view];

}
//16进制颜色#e26562与UIColor互转,设置View背景颜色
- (UIColor *) colorWithHexString: (NSString *)color
{
    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

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

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

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

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

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

    //b
    range.location = ;
    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];
}