TAILIEUCHUNG - Lập trình Wrox Professional Xcode 3 cho Mac OS part 16

Lệnh Redo thực hiện bổ sung của lệnh Undo. Nó có các hành động gần đây nhất chuyển sang làm lại danh sách, thực hiện nó một lần nữa, và thêm chúng vào trong lùi lại lịch sử. Cùng với nhau, các lệnh Undo và Redo giống như một cỗ máy thời gian, cho phép bạn bước về phía trước và phía sau thông qua lịch sử thay đổi fi le cho đến khi bạn fi thứ tình trạng của le fi bạn muốn. | 118 I CHAPTER 6 EDITING TEXT li Undoing a Cut or Copy command does not restore the previous contents of the system s clipboard. It only restores the state of the editor pane prior to the Cut command. The Redo command performs the complement of the Undo command. It takes the most recent action moved to the redo list performs it again and adds it to the undo history. Together the Undo and Redo commands are like a time machine allowing you to step forward and backward through the history of the file s changes until you find the state of the file you want. Any new change made to a file erases the redo list. If you go back in time and make a different choice you can no longer visit the future that contained the original choice. The Revert to Saved command empties both the undo and redo information for a file. The Save command does not alter the undo or redo information for a file. This means it is possible to undo changes made to a file after it has been saved. Whenever you try to undo the last action that occurred before a file was saved Xcode presents a dialog box like the one shown in Figure 6-25. m Warning ri MyVit 3 imp cementa VO id vi ewLJidLoad FIGURE 6-25 image re static cons static cons synthesize You are about to undo past the last point this file was saved. Do you want to do this Some developers find this dialog box annoying. Chapter 19 explains how to set the XCShowUndoPastSaveWarning advanced setting to disable that warning. SHELL SCRIPTS If you ve been around the Macintosh platform long enough to remember MPW the Macintosh Programmer s Workshop you may be missing one of its more intriguing features. Every text window in MPW was a live worksheet capable of executing any MPW command. In fact MPW made no real distinction between a text document and a shell window. This made for some interesting possibilities. Download at Spell Checking 119 Xcode .

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