在Swift中将字节数组转换为UIImage

Question

我想将字节数组转换为UIImage我的项目.
为此我在这里找到了一些东西.
之后,我尝试在swift中转换该代码但失败了.

这是我的代码的快速版本.

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
    }

但是我收到了错误:

EXC_BAD_INSTRUCTION

屏幕截图显示如下.

请帮忙解决这个问题.

Answer 1

如果您使用引用的示例数据，这些值不是UInts - 它们是带符号的Ints。传递负数UInt8()似乎确实会导致运行时崩溃 - 我认为它应该返回一个可选值。答案是使用bitPattern:带有签名的初始化程序，如下面的 Playground 示例所示：

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
}

因此你的函数应该是

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!!!
}