在Swift中将字节数组转换为UIImage [英] convert byte array to UIImage in Swift

问题描述

我想在我的项目中将字节数组转换为 UIImage 。

为此，我在

请帮助解决此问题。

解决方案

如果您使用引用的示例数据，则这些值不是 UInt s-它们被签名为 Int s。将负数传递给 UInt8（）确实确实会导致运行时崩溃-我以为它应该返回可选值。答案是使用带有 bitPattern：签名的初始化程序，如下面的Playground示例所示：

  let o = Int8（-127）
 print（o.dynamicType）//可选（< Int8>）
 //这是可选的，因此我们需要解开它... 
如果让x = o {
 print（x）// -127，如预期的那样
 // let b = UInt8（x）//运行时崩溃
 let b = UInt8（bitPattern：x）// 129，因为它应该是
} 
  

因此您的函数应该是

  func convierteImagen（cadenaImagen：String）-> UIImage？ {
 var字符串= cadenaImagen.componentsSeparatedByString（，）
 var字节= [UInt8]（）
对于0中的i。 strings.count {
 if letsignedByte = Int8（strings [i]）{
 bytes.append（UInt8（bitPattern：signedByte））
} else {
 //做点什么出现这种错误情况
} 
} 
让datos：NSData = NSData（bytes：bytes，length：bytes.count）
 return UIImage（data：datos）//注意可选的。不要强行拆开！！！ 
} 
  

I want to convert byte array to UIImage in my project.
For that I found something here.
After that I tried to convert that code in swift but failed.

Here is my swift version of the code.

func convierteImagen(cadenaImagen: NSMutableString) -> UIImage {
        var strings: [AnyObject] = cadenaImagen.componentsSeparatedByString(",")
        let c: UInt = UInt(strings.count)
        var bytes = [UInt8]()
        for (var i = 0; i < Int(c); i += 1) {
            let str: String = strings[i] as! String
            let byte: Int = Int(str)!
            bytes.append(UInt8(byte))
//            bytes[i] = UInt8(byte)
        }
        let datos: NSData = NSData(bytes: bytes as [UInt8], length: Int(c))
        let image: UIImage = UIImage(data: datos)!
        return image
    }

but I'm getting error:

EXC_BAD_INSTRUCTION

which is displayed in screenshot as follow.

Please help to solve this problem.

解决方案

If you are using the example data that you quoted, those values are NOT UInts - they are signed Ints. Passing a negative number into UInt8() does indeed seem to cause a runtime crash - I would have thought it should return an optional. The answer is to use the initialiser using the bitPattern: signature, as shown in the Playground example below:

let o = Int8("-127")
print(o.dynamicType) // Optional(<Int8>)
// It's optional, so we need to unwrap it...
if let x = o {
    print(x) // -127, as expected
    //let b = UInt8(x) // Run time crash
    let b = UInt8(bitPattern: x) // 129, as it should be
}

Therefore your function should be

func convierteImagen(cadenaImagen: String) -> UIImage? {
    var strings = cadenaImagen.componentsSeparatedByString(",")
    var bytes = [UInt8]()
    for i in 0..< strings.count {
        if let signedByte = Int8(strings[i]) {
            bytes.append(UInt8(bitPattern: signedByte))
        } else {
            // Do something with this error condition
        }
    }
    let datos: NSData = NSData(bytes: bytes, length: bytes.count)
    return UIImage(data: datos) // Note it's optional. Don't force unwrap!!!
}

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