sessionOutput.outputSettings = [AVVideoCodecKey: AVVideoCodecTypeJPEG]

XCode称’AVVideoCodecTypeJPEG’已重命名为’AVVideoCodecType.jpeg’,’AVVideoCodecTypeJPEG’已在Swift 3中废弃,它建议将’AVVideoCodecTypeJPEG’替换为’AVVideoCodecType.jpeg’

在这之后,XCode说’jpeg’仅适用于iOS 11.0或更高版本.

问题是我必须使用iOS 10并且想要使用Swift 4.

有没有任何解决方案可以在iOS 10的Swift 4中使用这样的功能？

if #available(iOS 11.0,*) {
    sessionOutput.outputSettings = [AVVideoCodecKey: AVVideoCodecType.jpeg]
} else {
    sessionOutput.outputSettings = [AVVideoCodecKey : AVVideoCodecJPEG]
}

在使用下面的帮助后,这是我目前的实施.但是,它出现了编译错误;

Expected member name or constructor call after type name &
Consecutive statement on a line must be separated by a ;

这是我正在使用的代码：

SKAction *pulseUp = [SKAction.scaleto(3.0,duration: 3.0)]
SKAction *pulseDown = [SKAction.scaleto(1.0,duration: 3.0)]
SKAction *pulse = [SKAction.sequence(pulseUp,pulseDown)]
SKAction *repeat = [SKAction repeatActionForever:pulse]]
[self.playButton runAction: repeat]

任何帮助将不胜感激.

let pulseUp = SKAction.scale(to: 3.0,duration: 1.0)
    let pulseDown = SKAction.scale(to: 0.5,duration: 1.0)
    let pulse = SKAction.sequence([pulseUp,pulseDown])
    let repeatpulse = SKAction.repeatForever(pulse)
    self.playButton.run(repeatpulse)

NSMutableAttributedString *res = [self.richTextEditor.attributedText mutablecopy];

[res beginEditing];
__block BOOL found = NO;
[res enumerateAttribute:NSFontAttributeName inRange:NSMakeRange(0,res.length) options:0 usingBlock:^(id value,NSRange range,BOOL *stop) {
    if (value) {
        UIFont *oldFont = (UIFont *)value;
        UIFont *newFont = [oldFont fontWithSize:oldFont.pointSize * 2];
        [res removeAttribute:NSFontAttributeName range:range];
        [res addAttribute:NSFontAttributeName value:newFont range:range];
        found = YES;
    }
}];
if (!found) {
    // No font was found - do something else?
}
[res endEditing];
self.richTextEditor.attributedText = res;

我试图通过迭代每个属性来更改NSMutableAttributedString中的字体.我很高兴听到有更好的方法,但如果有人能帮助我翻译上述内容,我会感到非常满意.

一个区别是这个实现使用可选的转换(如？),我这样做是为了演示这个概念.实际上,这不需要是可选的,因为NSFontAttributeName保证提供UIFont.

var res : NSMutableAttributedString = NSMutableAttributedString(string: "test");

res.beginEditing()

var found = false

res.enumerateAttribute(NSFontAttributeName,inRange: NSMakeRange(0,res.length),options: NSAttributedStringEnumerationoptions(0)) { (value,range,stop) -> Void in
    if let oldFont = value as? UIFont {
        let newFont = oldFont.fontWithSize(oldFont.pointSize * 2)
        res.removeAttribute(NSFontAttributeName,range: range)
        res.addAttribute(NSFontAttributeName,value: newFont,range: range)
        found = true
    }
}

if found == false {

}

res.endEditing()

dataToHex Objective C代码主要使用printf格式：

- (Nsstring *)dataToHex:(NSData *)data
{
    NSMutableString *str = [NSMutableString stringWithCapacity:100];
    const unsigned char *p = [data bytes];
    NSUInteger len = [data length];
    for(int i=0; i<len; ++i) {
      [str appendFormat:@"%02.2X",p[i]];
    }
    return str; 
}

逆向翻译是：

- (NSData *)hexToData:(Nsstring *)str 
{
    const char *ptr = [str cStringUsingEncoding:NSASCIIStringEncoding];
    NSUInteger len = [str length]/2;
    NSMutableData *data = [NSMutableData dataWithCapacity:len];
    while(len--) {
        char num[5] = (char[]){ '0','x',0 };
        num[2] = *ptr++;
        num[3] = *ptr++;
        uint8_t n = (uint8_t)strtol(num,NULL,0);

        [data appendBytes:&n length:1];
    }
    return data;
}

通过“巧妙地”覆盖ASCII数组中的两个字节,“0xXX”字符串将转换为一个字节,然后将其附加到可变数据对象.

既然我在Swift编码,我需要相同的功能,但没有发现任何类似Swift上面代码的帖子.

func dataToHex(data: NSData) -> String
{
    var str: String = String()
    let p = UnsafePointer<UInt8>(data.bytes)
    let len = data.length

    for var i=0; i<len; ++i {
        str += String(format: "%02.2X",p[i])
    }
    return str
}

但是,给定一个Nsstring对象,转换回NSData对象有点困难.如果您在模拟器中进行测试,从真实设备获得字符串标记,并且需要它来注册服务,则可能需要执行此操作.

我采用的第一种方法试图复制我之前使用的代码,通过创建一个包含字符对的字符串,并调用strtol：

func hexToData0(str: Nsstring) -> NSData {
    let len = str.length/2
    var data = NSMutableData(capacity:len)!
    var num: [Int8] = [ 0,0 ]
    let ptr = str.cStringUsingEncoding(NSUTF8StringEncoding)

    for var i=0; i<len; ++i {
        num[0] = ptr[i*2+0]
        num[1] = ptr[i*2+1]
        var n = UInt8 ( strtol(&num,nil,16) )

        data.appendBytes(&n,length:1)
    }
    return data;
}

我只觉得strtol有点像黑客,所以我使用NSScanner做了同样的代码大小相同,但效率最低：

func hexToData1(str: Nsstring) -> NSData {
    var data = NSMutableData(capacity: str.length/2)!
    for var i = 0; i<str.length; i+=2 {
        let r = NSRange(location: i,length: 2)
        let s = str.substringWithRange(r)
        let sc = NSScanner(string: s)

        var val: UInt32 = 0
        let ret = sc.scanHexInt(&val)
        if ret {
            var b = UInt8(val)
            data.appendBytes(&b,length: 1)
        } else {
            assert(false,"Yikes!")
        }
    }
    return data
}

然后,我想到我可以在Swift中完成所有工作,不需要达尔文或基金会,而代价是更多的代码：

// Swift 4
func hexToData(str: String) -> Data {
    let len = str.count/2
    var data = Data(capacity:len)
    let ptr = str.cString(using: String.Encoding.utf8)!

    for i in 0..<len {
        var num: UInt8 = 0
        var multi: UInt8 = 16;
        for j in 0..<2 {
            let c: UInt8 = UInt8(ptr[i*2+j])
            var offset: UInt8 = 0

            switch c {
            case 48...57:   // '0'-'9'
                offset = 48
            case 65...70:   // 'A'-'F'
                offset = 65 - 10         // 10 since 'A' is 10,not 0
            case 97...102:  // 'a'-'f'
                offset = 97 - 10         // 10 since 'a' is 10,not 0
            default:
                assert(false)
            }

            num += (c - offset)*multi
            multi = 1
        }
        data.append(num)
    }
    return data;
}

我在我的代码中使用了最终的hexToData.