[英]string concatenate with nil object in swift
I am trying find string value from coredata entity which some time return either string value or nil value. 我正在尝试从coredata实体中查找字符串值,该实体有时会返回字符串值或nil值。 I have to join that value with another string but when its return nil application crashed my code snippet
我必须将该值与另一个字符串连接起来,但是当它的返回nil应用程序崩溃时,我的代码片段
let objtest = (TblObjectValue.findOrCreate(["objectId":dicCurrent.valueForJSON("Id")]) as TblObjectValue)
tablecell.lblTitle?.text = "Value: "+objtest.displayValue!
Where TblObjectValue is NSManagedObject and objectId(NSString) and displayValue(NSString) are attribute of TblObjectValue entity application crash if displayValue is null
如果displayValue为null,则其中TblObjectValue是NSManagedObject,而objectId(NSString)和displayValue(NSString)是 TblObjectValue实体
application crash if displayValue is null
属性
i want it in one line
beacuse i used following code many time in my project i want it in one line
因为我在项目中多次使用以下代码
tablecell.lblTitle?.text = (dicCurrent.valueForJSON("CardLabel") as? String)!+": "+(TblObjectValue.findOrCreate(["objectId":dicCurrent.valueForJSON("Id")]) as TblObjectValue).displayValue!
Check it before do anything: 在执行任何操作之前先检查一下:
if objtest.displayValue != nil {
tablecell.lblTitle?.text = "Value: "+objtest.displayValue!
}
Doesn't 不
tablecell.lblTitle?.text = "Value: "+ (objtest.displayValue ?? "")
do the trick? 绝招?
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